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Polymerization of p-n-hexyloxyphenylacetylene (pHPA) by using a [Rh(norbornadine)Cl]2-triethylamine catalyst was carried out at room temperature to afford stereoregular helical poly(p-n-hexyloxyphenylacetylene)s (PpHPAs). When ethanol and n-hexane were used as polymerization solvents, a bright yellow PpHPAs, poly(Y) with Mn = 8.5 × 104 and its purple red polymer, poly(R) with Mn = 5.3 × 104 were obtained in 95% yields and 84% yields, respectively. Diffuse reflective UV–vis spectra of poly(Y) and poly(R) in solid phase showed different broad absorption peaks at 445 and 575 nm, respectively. X-Ray diffraction patterns of poly(Y) and poly(R) showed typical columnar structures assignable to cis-transoid and cis-cisoid structures, respectively, which were also supported by molecule mechanics calculation. Poly(Y) was irreversibly transformed to a reddish-black polymer, poly(Y-B), which columnar diameter was nearly the same as that of poly(R). Further, poly(Y) showed an exothermic peak in the differential scanning calorimetry trace at 80 °C for 1 h in N2 gas. Thus, these findings suggest a thermally irreversible rearrangement from an unstable cis-transoid form, poly(Y) with a stretched cis-transoid helix to a stable cis-cisoid form, poly(R), with a contracted cis-cisoid helix in the solid phase to give poly(Y→B) with the cis-cisoid form. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

The chiral isoquinuclidine derivative, 2-azabicyclo[2.2.2]octane ring system, endo -(7 R )- 3 was obtained in good yield with excellent diastereoselectivity (up to 92% de) by Diels–Alder reaction of 1-(phenoxycarbonyl)-1,2-dihydropyridine 1 with N -acryloyl-(4 S )-4-benzyloxazolidin-2-one (4 S )- 2 using titanium-(2 R ,3 R )-TADDOLate 4 as a chiral Lewis acid catalyst in toluene at 0 °C. On the other hand, endo -(7 S )- 3 was obtained in good yield with excellent diastereoselectivity (up to 97% de) by Diels–Alder reaction of 1 with (4 R )- 2 using Cu(OTf) 2 /(4 S ,4′ S )-bis(oxazoline) catalyst 8 as a chiral Lewis acid catalyst in dichloromethane at 0 °C. In these reactions, the choice of solvent and the combination of titanium-(2 R ,3 R )-TADDOLate 4 {or Cu(II)/(4 S ,4′ S )-bis(oxazoline) 8 } and dienophile (4 S )- 2 {or (4 R )- 2 } are very important. The stereochemistry of endo -(7 R )- 3 has been established to be (1 R ,4 S ,7 R ) and the reaction mechanism is proposed.

Propargyl esters, HC CCH 2 OCOC n H 2n+1 ( 1 : n = 3, 2 : n = 5, 3 : n = 9, and 4 : n = 13), were polymerized using a [Rh(nbd)Cl] 2 catalyst and cocatalyst in an appropriate solvent at 0 °C and 40 °C. Number average molecular weights, M n of the resulting polymers, poly( 1 )–poly( 4 ), were 8000–54,000, and its dispersities ( M w / M n )s and the yields were estimated to be 1.6–3.6 and ca . ∼99%, respectively. These polymers were soluble in CHCl 3 , CH 2 Cl 2 , and THF, and insoluble in CH 3 OH and DMF. The amines, e.g., 2,6-dimethylpyridine and triethylamine worked well as the cocatalysts for the polymerization to give the yields, 93% and 88%, respectively. Further N , N- diethylaniline gave the maximum in cis %, 74%, although pyridine, aniline, pyrrole or imidazole did not work effectively. Remarkable line broadening phenomenon, LBP observed in the 1 H NMR spectra of poly( 1 ) and poly( 2 ) prepared at 0 °C or 40 °C, and poly( 3 ) prepared at 40 °C was correlated with the polymerization temperature and the radical concentration generated in the polymer. The LBP was interpreted by the dipole–dipole interaction between the protons in the polymer and unpaired electrons due to carbon radicals generated by the rotational scission of the cis C C bonds during the polymerization. Their UV–vis spectral shape of poly( 1 )–poly( 4 ) depended on the polymerization temperature and/or the alkyl chain length in the polymer. The XRD powder patterns of poly( 3 ) prepared at 0 °C, and poly( 4 )s prepared at 0 °C and 40 °C showed layer crystal structures with a slightly bent herringbone confirmed by molecular mechanics calculation. The λ max values of poly( 4 ) prepared at 40 °C in methanol showed 317 nm and 340 nm in the solution and on the alumina, respectively.

The poly(propargyl acetate) ( A ) having a helical cis – transoid structure was stereospecifically prepared using the Rh complex catalyst, [Rh(norbornadiene)Cl] 2 , in MeOH or NEt 3 solvent at 0 and 40 °C in moderate yield. Electron spin resonance (ESR) analysis of the polymer revealed the formation of the cis ( B ) and trans ( C ) radicals which were produced through the thermal rotational scission of the helical cis C C bonds in the main-chain during the polymerization. The spatial and geometrical structure was successfully deduced using the two analogues’ polymers in which either methyl or methylene group is deuterated, by the aide of computer simulation of the observed ESR spectra together with the calculation of spin density of the two radicals.

Flav-3-enes were prepared in excellent yields (up to 98%) by reductive elimination of flav-3-ene-4-triflates in the presence of palladium acetate, formic acid and tri-n-buthylamine.

The Diels–Alder reaction of 1,2-dihydropyridine derivatives (1-phenoxycarbonyl-1,2-dihydropyridine 1 or 1-methoxycarbonyl-1,2-dihydropyridine 4) with N-acryloyl (1S)-2,10-camphorsultam (1S)-2 {or N-acryloyl (1R)-2,10-camphorsultam (1R)-2} in the presence of Lewis acid, such as titanium tetrachloride, zirconium tetrachloride, and hafnium tetrachloride afforded the endo-cycloaddition product, 2-azabicyclo[2.2.2]octane derivatives in good yields with excellent diastereoselectivity. The absolute stereochemistry assignment of the endo-cycloaddition product (1S)-5a starting from N-acryloyl (1S)-2,10-camphorsultam (1S)-2 has been established to be (1S,4R,7S) and the reaction mechanism was proposed.

Highly polarized 4′5′-bis(methylthio), 4′,5′-ethylenedithio, and 4′,5′-ethylenedioxy-4,5-dithiocyanotetra-thiafulvalenes [BMT-TTF(SCN)2, EDT-TTF(SCN)2, and EDO-TTF(SCN)2] were synthesized in moderated yields from 2-cyanoethylthio-TTF derivatives. EDO-TTF(SCN)2 formed a CT complex with TCNQF4 due to its moderate electron donating ability. The packing structure of the CT complex obtained by X-ray analysis shows many intermolecular interactions through the S•••S, S•••N, C•••N, and N•••O contacts. The strong intermolecular interactions composed of the donor–donor, donor–acceptor, and acceptor–acceptor combinations enhance the dimensionality of the molecular network in the CT-complex. †Crystallographic data for 1c•TCNQF4 have been deposited with the Cambridge Crystallographic Data Centre as Supple-mentary Publication No. CCDC 715536.

A simple and efficient synthesis of tribenzohexadehydro[12]annulene and its derivatives was carried out using coupling reaction of acetylenes with iodoarenes in the presence of catalytic amounts of CuI and PPh,, together with three equivalents of K 2 CO 3 in DMF. This synthetic procedure was applied to the synthesis of a large annulenoannulene derivative.

Reactions of perfluoroalkyl iodides with styrene and its derivatives were investigated under radical conditions in the presence of oxygen. The photochemical reaction of styrene with CF3(CF2)5I in the presence of tributyltin hydride or tris(trimethylsilyl)silane under an oxygen atmosphere afforded the corresponding perfluoroalkylated alcohols in moderate yields together with CF3(CF2)5H. However, the photochemical reactions of styrene and its derivatives with CF3(CF2)nI (n = 3, 5) in the presence of hexabutylditin under oxygen produced the perfluoroalkylated alcohols in good yields. Furthermore, the reactions of styrenes with CF3(CF2)nI (n = 3, 5, 9) and Na2S2O4 in the presence of a base under air formed the same alcohols in good yields. The alcohols were found to provide a novel type of α-fluoroalkylated styrenes by acidic dehydration. Perfluoroalkylated α,β-unsaturated ketones were synthesized by oxygenative perfluoroalkylations of α-chlorostyrene and its derivatives using CF3(CF2)nI (n = 3, 5) under radi...

We examined three autopsy cases of globoid cell leukodystrophy (GLD) with different survival, using immunohistochemistry and in situ nick end labeling (ISEL). The white matter lesion was pronounced in the corona radiata, corpus callosum and cerebellar peduncles in three cases, where a spongy state developed, in addition to the neuronal loss in the thalamus, cerebellum and inferior olivary nucleus. Ramified microglia, being immunoreactive for ferritin and HLA-DR alpha, were scattered in the white matter, and some of them also had immunoreactivity for TNF-alpha. Both the small-sized and large-sized globoid cells showed immunoreactivity for ferritin KP-1 and NCAM, while some of the small-sized globoid cells were also immunoreactive for HLA-DR alpha and TNF-alpha. As the survival became longer, the occurrence of the globoid cells decreased, however, they were commonly observed in the corpus callosum and cerebellar peduncle in three cases. T lymphocytes immunoreactive for LCA, UCHL-1 and CD3 were increased around the vessels in the white matter. ISEL stained nuclei of mononuclear cells in the white matter in two cases with short survival, although the cell origin was not verified. ISEL also visualized a few nuclei of the small-sized globoid cells in one case. On the other hand, immunostainings against cell death proteins such as bcl-2 family members and p53 failed to identify any significant changes. These data suggest that the immunological step and to a lesser extent the apoptotic process may partly be involved in the myelin breakdown and glial pathology in GLD, as reported in the twitcher mouse, a murine model of GLD.

Syntheses of the macrocyclic spermidine alkaloids (±)-celacinnine ( 1 ) and (±)-dihydroperiphylline ( 2 ) as well as the related spermine alkaloid (±)-verbascenine ( 3 ) were accomplished by means of sequential ring expansions of smaller lactam rings. Three ring expansion methods were employed: (1) transamidation of N -(aminoalkyl)lactams, (2) β-lactam-lactim ether condensation followed by reductive cleavage of the bicyclic 4-oxotetrahydropyrimidine product with NaBH 3 CN/AcOH and (3) bicyclic acyl hydrazine formation followed by N–N bond cleavage with Na/NH 3 . Each synthesis features ring expansion of a 4-phenylazetidin-2-one intermediate that undergoes transamidative ring expansion or lactim ether condensation.

Seventeen peralkylated four- and five-membered heteroatom-containing silacycles [R1R2Si]nX [R1 = iPr and/or R2 = tBuCH2; n = 3; X = CH2 (1a, 1b), NR3 (R3 = C6H11) (3a−d), O (5a−c), and n = 4; X = CH2 (2a, 2b), NR3 (R3 = C6H11 or Pr) (4a−d), and O (6a, 6b)] have been synthesized and characterized. The structural features of twelve compounds − 1b, 3a−d, and 5b (Si3X) and 2a, 4a−c, 6a, and 6b (Si4X) − determined by X-ray analysis have been investigated and geometrical differences between the silacycles bearing neopentyl groups and those with isopropyl groups as bulky substituents on silicon atoms have been identified. The ring strain energies for the compounds [R2Si]nX [n = 3, 4; R = Me, iPr; X = CH2, N(iPr), NMe, O, SiH2], estimated by theoretical calculations at the PM3 level, are discussed in relation to experimentally ascertained structural features of the silacycles [R2Si]nX (n = 3, 4; R = iPr; X = CH2, NC6H11, O, SiR2). 29Si NMR spectra for 1−6 showed that the resonances for the α-silicon atoms attached to the heteroatoms X in the two ring-size series were shifted downfield by a deshielding effect due to an electronegative atom X; larger electronegativity (En) of X caused this effect at lower field. The chemical shifts of the Siα atoms showed a good linear correlation with the electronegativities of the heteroatoms X in the [R2Si]nX cycles. In the UV spectra for 1−6, little difference in the longest-wavelength absorption (LWA) maxima was observed for [(iPr)2Si]nX and [(tBuCH2)2Si]nX of the same ring size. The LWA bands for 1−6 and related compounds could be roughly classified into four groups: (a) [R2Si]3X (X = SiR2, GeR′2) λ = 286−300 nm; (b) [R2Si]3X (X = CH2, NR3, O) (1, 3, 5), λ = 230−250 nm; (c) [R2Si]4X (X = SiR2, GeR′2) λ = 274−280 nm; (d) [R2Si]4X (X = CH2, NR3, O) (2, 4, 6), λ = 250−260 nm. With the aid of the ionization potentials and the transition energies (ET), the HOMO and LUMO levels for the series of compounds and the related ones were experimentally evaluated. The HOMO and LUMO levels thus obtained for [R2Si]3X and [R2Si]4X (R = iPr and tBuCH2; X = SiR2, GeR′2, CH2, NC6H11, O) are discussed in terms of the calculated values and frontier orbitals on the basis of PM3 levels. The theoretical prediction for bond scission in the silacycles [(iPr)2Si]nX (n = 3, 4; X = CH2, NMe, O) in which the HOMOs and LUMOs have Si−Si bonding and antibonding character, respectively, was corroborated by the good agreement with experimental results from photolysis of the silacycles [R2Si]nX (n = 3, 4; R = iPr and tBuCH2; X = CH2, NC6H11, O), with bond scission occurring only at the Si−Si bonds, and not at the Si−X bonds. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Two isomeric 1,8-[1,8-naphthylenebis(2,2′-bithienyl-5,5′-ylene)]naphthalenes (major and minor isomers) were synthesized using the coupling reaction of 1,8-di(5-lithio-2-thienyl)naphthalene with CuCl2. The major isomer easily isomerized photochemically to yield the minor isomer. The redox and fluorescence behavior of the two isomers reflect both face-to-face interaction of the 2,2′-bithienyl-5,5′-ylene units and deformation of the naphthalene moieties.

Nickel-catalyzed oligomerization of trans-1,2-dibromobenzocyclobutene formed cyclic dimers and trimers. Upon heating, the major anti-cyclic trimer afforded a cage compound, whereas the minor syn-trimer produced all-Z-tribenzo[12]annulene. Dehydrogenation of the anti-trimer with DDQ resulted in the formation of an indenoazulene derivative, and a similar reaction of the syn-trimer yielded a bowl-shaped system. All-Z-tribenzo[12]annulene was also synthesized using a stepwise route starting from o-diiodobenzene and o-ethynylbenzyl alcohol, the overall yield being 22%. All-Z-tribenzo[12]annulene behaved like π-prismand and formed chromium(0) tricarbonyl and silver(I) complexes.

The copper(I) and silver(I) complexes of all-Z-tribenzo[12]annulene were synthesized and the structures were determined by X-ray analysis. The trigonal olefinic cavity of the [12]annulene incorporates copper and silver cations to produce stable complexes, whereas the gold(I) complex was unstable, yielding a cyclization product via isomerization of the Z-double bonds.

A convenient method for the one-pot synthesis of heterocyclic compounds bearing a perfluoroalkyl group from α-chlorostyrenes via perfluoroalkylated α,β-unsaturated ketones has been developed.

Biphenylene and some of its 2,3,6,7- and 1,8-substituted derivatives were synthesized using the CuCl2-mediated intramolecular coupling of an organozinc species prepared from 2,2′-dilithiobiaryls with one or two molar equiv. of ZnCl2 or ZnBr2 in THF. Although most of the reactions of 2,2′-dilithiobiaryls with CuCl2 in THF in the absence of ZnCl2 or ZnBr2 led to biphenylenes as a major product, similar reactions of the organozinc species with CuCl2 in THF produced biphenylenes in much better yields, due to smooth transmetallation and reductive elimination reactions. In particular, the copper-mediated cyclization of benzannelated organozinc intermediates, prepared from equimolar proportions of 2,2′-dilithiobiaryls with ZnCl2, proceeded smoothly and selectively to afford the desired biphenylenes in 46–81% yield except for the reaction of the zinc intermediate derived from 4,4′,5,5′-tetramethoxy-2,2′-dilithiobiphenyl with ZnCl2 (1.0 molar equiv.). The reaction of the tetramethoxy-substituted organozinc species with CuCl2 produced 2,3,6,7,10,11,14,15-octamethoxytetraphenylene as a major product in 67% yield.

Enantioselective Diels–Alder reactions of 1,2-dihydropyridines with acroleins using a novel chiral oxazolidine organocatalyst afforded chiral isoquinuclidines that is an efficient synthetic intermediate of oseltamivir, with fairly good chemical yield and excellent enantioselectivity (90%, up to >99% ee).

Crystal structures of the silver complexes derived from tetrabenzo[16]annulene with AgOTf and AgClO(4) are different, although these two complexes show similar (1)H NMR spectra reflecting a similar clathrate structure in solution. The silver complex of pentabenzo[20]annulene with AgClO(4) adopts a clathrate structure both in the solid state and in solution.

We report here an efficient route to the synthesis of highly fluorescent hexaaryl[3]radialenes using the oligomerization of ate-type copper carbenoids, followed by cyclization with hexamethylditin and Pd(PPh3)4; the structures of the [3]dendralene and hexaaryl[3]radialenes were determined by X-ray crystallographic analysis.

A new and general method for preparing Fischer-type alkoxycarbene complexes 1 is reported. This method involves the alkylation of acylate complexes 7 with alkyldiphenylsulfonium salts 10 with a variety of functionalized alkyl groups. The alkylation of tetramethylammonium pentacarbonyl(1-oxyalkylidene)chromate(0) 7a-c, tetramethylammonium pentacarbonyl(1-oxymethylidene)molybdate(0) 7d, and pentacarbonyl(1-oxymethylidene)tungstate(0) 7e with alkyldiphenylsulfonium salts 10 proceeded smoothly under mild conditions to give the corresponding alkoxycarbene complexes 12-39 in good to high yields. Competitive alkylation of 7a with methyl-11 and isopropyldiphenylsulfonium tetrafluoroborate 40 shows a higher reactivity of the isopropyl group, suggesting the participation of an S-O sulfurane intermediate 41.

Selenobenzophenone reacts as a diene with dimethyl acetylenedicarboxylate (DMAD) to lead to dimethyl 1H-1-diphenylmethyl-1-phenyl-2-benzoselenopyran-3,4-dicarboxylate (5c) in moderate yield; the initial [4 + 2] cycloaddition is followed by the addition of another 1 mol equiv of selenobenzophenone. The reaction might proceed through carbene insertion of the primary cycloadduct. On the other hand, 4,4'-dimethoxyselenobenzophenone combines as a diene with DMAD furnishing dimethyl 1H-1-p-methoxyphenyl-6-methoxy-2-benzoselenopyran-3,4-dicarboxylate (4a). The reaction of benzoselenopyran derivative (4) with diaryldiazomethanes afforded another type of carbene insertion product.

Reaction of 5-methylene-1,3-dioxepanes derived from oxaphospholanes and paraformaldehyde with trimethylsilyl trifluoromethanesulfonate in the presence of a base yielded novel, exo formyl tetrahydropyran derivatives in good yields.

An overview of recent studies on asymmetric synthesis of biologically interesting compounds utilizing chiral sulfoxides is described. The reaction mechanism of some asymmetric syntheses is also discussed.

We present the clinicopathological and immunohistochemical findings obtained at autopsy from the central nervous system (CNS) of patients with chronic encephalomyelitis (CEM; n= 5) with prominent involvement of the brain stem and those with neuro-Behct's disease (NBD; n= 3). The clinical findings in these patients were similar except for the absence of mucocutaneo-ocular symptoms in CEM. It was not possible to differentiate CEM from NBD based on neuropathology. Immunohistochemical studies revealed that UCHL1+ T cell infiltration in all cases examined was prominent not only in the perivascular area but also in grossly normal-appearing areas which lacked necrosis or degenerative changes. The widespread UCHL1+ cell infiltration observed throughout the CNS including cerebral cortex and white matter might be responsible for the psychiatric disturbances which were manifest in these diseases. Pseudobulbar paresis and spastic tetraparesis could be explained by small necrotic foci that were mainly distributed in brain stem and spinal cord.

E-(R)-(+)-8-Dodece-11-olide, which is known as recifeiolide, was synthesized by a six-step reaction starting from (R)-(+)-propene oxide in a total yield of 53 %. The key step of this synthesis is the preparation of (R)-(−)-methyl 11-hydroxy-8-dodecenate using (R)-(−)-5-methyl-2,2,2-triphenyl-1,2λ5-oxaphospholane. Be using this method, enantiomerically pure 13- and 14-membered macrolides were also synthesized.

We examined the occurrence of apoptotic cell death in the autopsied brains of four patients with Werdnig Hoffmann disease (WH), using TdT-mediated in DIG-dUTP nick end labeling (TUNEL) and immunohistochemistry for apoptosis-related proteins. Three of the four patients, aged over 6 months, exhibited TUNEL-positive cells in the lateral nuclei of the thalamus, and one of the three patients also had TUNEL-positive cells in the cerebral cortex. The labeled nuclei did not show characteristic features such as nuclear fragmentation or apoptotic bodies, and synaptophysin-positive granules were observed around some of the TUNEL-positive cells, although none of the antibodies against glial markers could visualize TUNEL-positive cells. TUNEL-positive cells were not observed in other regions examined, including the spinal cord, medulla and cerebellum or in the brains of three age-matched controls. There were neither immunopositive structures for bcl-2 or p53 nor alteration of in situ expression of bcl-xs/l or bax in any subject, and the TUNEL-positive cells lacked immunopositivity against apoptosis-related proteins. The presence of these TUNEL-positive cells might suggest latent neurodegeneration in the thalamus before central chromatolysis of neurons or neuronal loss appears, although it is not clear whether apoptotic cell death is involved in this degenerative process.

New bridged tetrathiafulvalene derivatives have been synthesized from ethylenedithiotetrathiafulvalene (EDT-TTF) in moderate to good yields using the lithiation-alkylation procedure. The X-ray analysis of the bridged molecule shows a spider-like structure.

The heat capacity of crystalline 4,4‴-difluoro- p -quaterphenyl was measured between 8 and 303 K by adiabatic calorimetry. A broad heat-capacity anomaly was found at 200.5 ± 0.5 K and attributed to a phase transition associated with molecular twisting. Some thermodynamic properties including those concerning the phase transition are reported.

1,1-Diferrocenylethylenes have been synthesized efficiently by palladium-catalyzed cross-coupling reaction. The interaction of the two ferrocene units has been investigated in the neutral, monocationic and dicationic states using spectroscopic analyses.

A deuterium-induced phase transition has been discovered in a molecular crystal of tolane- d 10 by powder X-ray diffraction and differential scanning calorimetry (DSC) experiments. The phase transition is of first order. DSC measurements on solid binary solutions of tolane- h 10 and tolane- d 10 have shown that there is a critical point on the temperature-composition phase diagram of this binary system.

Both enantiomers of (S)- and (R)-4-phenyl-1,5-diazacyclooctan-2-ones (7) were synthesized stereoselectively with good optical purity by the asymmetric conjugate addition of pyrazolidine to optically active vinyl sulfoxides, t-butyl (E)-2-[(R)- and (S)-p-tolylsulfinyl]cinnamates, respectively. Starting from 7, a synthesis of optically active homaline was achieved.

The reaction of tropone or 2-substituted tropone with the anions derived from methylmethoxycarbene complexes of chromium and tungsten gave pentacarbonyl(1-oxazulen-2-ylidene)chromium and -tungsten complexes.

Platinum complexes of C60 and C70 were synthesized and characterized by using spectroscopic analysis. The X-ray data of the C60-platinum complex containing no solvent of crystallization afforded the definite bond lengths and angles.

The heat capacity of 4,4″-difluoro- p -terphenyl was measured between 8 and 303 K by adiabatic calorimetry. A phase transition associated with molecular twisting was observed as a sharp peak at (127.05 ± 0.05) K. The enthalpy and the entropy of transition were determined as (180 ± 20) J mol −1 and (1.41 ± 0.15) J K −1 mol −1 , respectively. It is pointed out that this phase transition lies in the border region between an order-disorder and displacive-type transition under normal pressure. The apparatus used for calorimetry is described.

The heat capacity of crystalline 4,4‴-difluoro- p -quaterphenyl was measured from 8 K to 303 K by adiabatic calorimetry. A broad anomaly was detected between 140 and 250 K and attributed to a structural phase transition associated with molecular twisting. The temperature, the enthalpy and the entropy of transition were determined as (200.5 ± 0.5) K, (322 ± 20) J·mol −1 and (1.65 ± 0.10) J·K −1 ·mol −1 , respectively. The properties of the transition are compared with those of unsubstituted and fluorine-substituted p -polyphenyls (of two to four benzene rings in a molecule) in the light of a unified model of displacive and order-disorder types of structural phase transition.

Low-temperature X-ray diffraction experiments were performed on 4,4″-difluoro-p-terphenyl (DFTP) and 4,4‴-difluoro-p-quaterphenyl (DFTP). The structure analyses were performed for the high- temperature phases and the librational motion of the benzene rings was analyzed. The super-lattice reflections were found in DFQP below about 200 K on the same positions as the low-temperature phase of p-quaterphenyl. In DFTP, the satellite reflections with small wavevector component δc (about 1 6 ) along the c∗-axis were found below the transition temperature.

A mild and efficient synthetic methodology for obtaining the compounds (IV), which are useful intermediates for the synthesis of flavonoids, is developed.

4,4″-Difluoro-p-terphenyl and 4,4″′-difluoro-p-quaterphenyl were synthesized and their crystal structures were determined at room temperature. These are isostructural to p-terphenyl and p-quaterphenyl, respectively. Some “disorder” in the inner benzene ring orientation was detected and resolved by the split-atom method. A rigid-body librational analysis of each benzene ring around the long molecular axis was performed. A rough estimate of the barrier height of the planar conformation for 4,4″-difluoro-p-terphenyl was obtained as being about 1 kJ mol−1. The results are compared with the properties of p-terphenyl and p-quaterphenyl, and the effect of fluorine-substitution on the molecular properties is discussed in relation to the low-temperature phase transitions.

Optically active 2- and 3-hydroxyalkyltriphenylphosphonium salts were prepared by the optical resolution of their 2,3-di-O-benzoyltartrates. The reaction of these salts with butyllithium afforded the corresponding ylides, which reacted with aldehydes to give optically active (E)-homoallylic alcohols in good yields. 3-Hydroxyalkyltriphenylphosphonium salts were converted into the corresponding diphenylphosphine oxides by the reaction with aq NaOH, which reacted with sodium hydride followed by the addition of benzaldehyde to afford optically active (Z)-homoallylic alcohols.

The Optically active 3,3-dialkyl-4-thianones 3 and 4 were prepared in moderate yields with about 90% enantiomeric purity using an asymmetric process involving a Michael-type alkylation of chiral 3-alkyl-4-thianimines with methyl vinyl ketone or methyl acrylate. The diketones 3 were then transformed into new heterocycles 5 by base-induced cyclization. 3-Methyl- and 3-allyl-3-(2-methoxycarbonylethyl)-4-thianone ((+)-4a and (+)-4b) were converted into the bicyclic lactones (−)-6 and (−)-7, respectively. The stereochemistry of the sulfone (+)-8 derived from the lactone (−)-6a was determined by a X-ray crystal structure analysis. Desulfurization of the lactone (−)-6b using nickel boride afforded the corresponding lactone (+)-9. A synthesis of optically active 2-alkyl-2-methyl-3-cyclopentenone (S)-(+)-15 via the Ramberg–Backlund reaction from the keto ester (R)-(+)-4a was also accomplished.

Enantioselective Diels–Alder reactions of 1,2-dihydropyridines with acroleins using a novel chiral oxazolidine organocatalyst afforded chiral isoquinuclidines that is an efficient synthetic intermediate of oseltamivir, with fairly good chemical yield and excellent enantioselectivity (90%, up to >99% ee).

Diaminosulfoxonium salts were prepared by alkylation of sulfonimidamides. Their physical properties were described. Their reaction with bases gave the corresponding ylides and sulfonimidamides. The intramolecular rearrangement of the ylides led to ortho substitution via intermediate cyclohexadienimines. Hydrogen transfer, accompanying rearomatization and the subsequent action of bases gave dihydro-2,1-benzisothiazole derivatives. These ylides were also found to react with aldehydes to afford epoxides in moderate yields.

Triaminosulfoxonium salts were synthesized by the oxidation of triaminosulfonium salts with sodium perbenzoate. The reaction of these salts with nucleophiles was carried out.

The reactions of dialkylphenylsulfonium salts (1) with several nucleophiles such as phenols, amine, enolate ion, and thiolate ions, have been investigated. The relative reactivities of the alkyl groups of sulfonium salts for the phenolate ion (hard nucleophile) were as follows; Me:Et:i-Pr =1.0:1.34:3.44. In the alkylation of the p-toluenethiolate ion (soft nucleophile) with 1, the opposite reactivity (Me:Et:i-Pr=1.0:0.22:0.03) was found. When a sulfonium salt (1e) having an optically active (S)-s-butyl group was reacted with a phenolate ion, an optically active (R)-s-butyl phenyl ether was obtained with an inversion of the configuration at the chiral carbon atom. A reaction mechanism via a sulfurane intermediate is proposed for the alkylation of the phenolate ion with alkylsulfonium salts. The relative reactivities for the alkylation of several nucleophiles with dialkylphenylselenonium salts (12) were also investigated.

Optically active (R)-(+)-l,5-diaza-4-phenylbicyclo[4.3.0]nonan-2-one (5) was prepared in high optical purity by diastereoselective conjugate addition of piperidazine to optically active (E)-(S)-1-(...

Enantioslective synthesis (>92% e.e.) of quaternary carbon centers through Michael-type alkylation of chiral imines of 3-alkyl-4-thianones with methyl acrylate and successive diastereoselective synthesis of optically active lactones are described