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Dioxomolybdenum complexes were examined as catalysts for the copolymerization of e-caprolactone (e-CL) and l-lactide (l-LA). The bis-[(5-OMe)salicylaldehydato]dioxomolybdenum complex completed the copolymerization after 20 h at 110 °C with 0.05 mol% of the catalyst to produce a copolymer in high yield. The microstructure of the copolymer was analyzed using 1H and 13C NMR spectroscopy and was determined to have a random structure. The r values calculated from the heterodiad analysis of the 1H NMR data were r LA = 0.91 and r CL = 0.93, and the L values calculated from the triad analysis of the 13C NMR data were L LA = 1.58 and L CL = 1.81. Other dioxomolybdenum complexes, such as cis-α MoO2[(3-MeO)DiMeSaltn], MoO2(acac)2 and (NH4)8[Mo10O34] exhibited comparable or slightly lower reactivity for the copolymerization. Consecutive polymerization of e-CL followed by l-LA afforded a block copolymer without trans-esterification.

A series of star-shaped poly(lactic acid)s with carboxylic acid terminal groups have been synthesized by direct poly-condensation of lactic acid in the presence of a poly-carboxylic acid core molecule with triphenylphosphonium trifluoromethanesulfonate (TPP-T) catalyst. These star-polymers had thermal properties not very much different from those of star-shaped poly(lactic acid) with hydroxyl terminal groups and linear poly(lactic acid), irrespective of the structure of the core molecule and number of polymer arms. Solubility and degradability of these star-polymers were, however, greatly enhanced compared to those of star-polymers with hydroxyl terminal groups and increased depending on the number of polymer arms. From the star-shaped polymers, a variety of ammonium salts and the corresponding carboxyamides were successfully prepared.

Synthesis of LL-lactide with high chemical, diastereomeric, and enantiomeric purities was achieved by depolymerization of oligo(lactic acid) in the presence of an onium salt catalyst.

The novel doubly borylated enolate is identified as an intermediate of the double aldol reaction of acetate esters. As a precursor to the formation of the doubly borylated enolate, carbon-bound boron enolates of carboxylic esters are spectroscopically characterized for the first time. When 2,6-diisopropylphenyl acetate (10d) is treated with c-Hex(2)BOTf (1.3 equiv) and triethylamine (1.5 equiv) in CDCl(3), the corresponding mono-enolate is formed as a mixture of oxygen- (11d) and carbon-bound (12d) forms in 71% and 20% yields, respectively. The structures of these enolates have been unambiguously determined by NMR spectroscopy. Investigation of the enolization of a series of substituted aryl acetates shows that the steric factor of the acetate affects the degree of the mono-enolate (as a mixture of oxygen- and carbon-bound enolates) and the doubly borylated enolate formation. Studies also revealed that oxygen- and carbon-bound boron enolates exist as equilibrium mixtures and that a proton transfer process occurs between oxygen- and carbon-bound enolates. The doubly borylated enolate formation is general for a variety of carbonyl compounds. Besides acetate esters, carbonyl containing compounds, such as acetic acid, dimethylacetamide, methoxyacetone, and 3-acetyl-2-oxazolidinone, also produce the doubly borylated enolates when treated with c-Hex(2)BOTf (2.5 equiv) and triethylamine (3.0 equiv). A plausible pathway of the double aldol reaction involving a carbon-bound boron enolate as a key intermediate is proposed.

Solvolysis of 4-alkoxycarbonyl-(or 4-acyl)-3-oxo-1,2,3,4-tetrahydroquinolizinium ylides (1-4) was studied and three types of reactions were found to proceed competitively. Thus, alcoholysis afforded the Chichibabin rearrangement products, 2,3-dihydro-2-indolizinones (5-8), solvolysis in trifluoroethanol or in aqueous methanol caused ring opening (and subsequent ester cleavage) to 2-alkoxycarbonylethylpyridinium-1-acetates 10, 15, and 16, and hydrolysis resulted in ring opening to 1-alkoxycarbonylmethylpyridinium-2-propionates 11 or 13 (and subsequently to 12 or 14). Characteristically, all the types of reactions proceeded significantly faster with t-butoxycarbonyl substituted ylides than with smaller alkoxycarbonyl substituted ones. The general mechanism for the solvolysis, involving a ketene intermediate, is proposed based on kinetic measurements.

症例は51歳男性, 7～8年前より右鼠径部腫瘤を自覚するも放置していた.その後腫瘤は著名に増大,体動困難を主訴として当科受診した.来院時右鼠径部から陰部にかけて約40cm大の表面平滑,弾性硬な腫瘤を形成していた.潰瘍,糜爛などの皮膚異状所見は認めなかった. CT・MRIでは境界明瞭,内部不均一な腹壁外腫瘤として描出した.悪性腫瘍を否定しきれず,また機能回復目的のため摘出術を施行した.手術所見では,一部精巣精索と癒着していたが,被膜に覆われ境界明瞭かつ可動性良好な腫瘤として認めた.摘出検体は, 40cm×28cm×15cm,重さ12.5kgの割面黄白色の腫瘤であり,病理組織学的所見はspindle cell lipomaであった.術後経過は良好であり再発徴候は認めていない.自験例の様な巨大spindle cell lipomaは稀であり,文献的考察を加え報告する.

The synthesis of BMPD, 1,3-bis(2-methylferrocenyl)propane-1,3-dione, was achieved via the Claisen condensation of a homochiral ferrocenecarboxylate and an acetylferrocene derived from the same chiral formylferrocene. Several metal complexes were prepared to exemplify the complexation ability of BMPD. A BMPD-yttrium complex was found to act as a new catalyst for silylcyanation of aldehydes with remarkable efficiency. As little as 0.2 mol% of the complex catalyzed the reaction of benzaldehyde and cyanotrimethylsilane to afford the cyanohydrin in 95% yield with 87% ee.

A new chiral reagent for syn-selective aldol reactions has been developed based on the recent finding that the stereochemistry of the boron-mediated aldol reaction of a carboxylic ester is controlled by the bulkiness of the alcohol moiety of the ester, by the proper choice of reagents, and by the enolization conditions. This readily available, inexpensive reagent has been utilized in studies directed towards the synthesis of the macrolide tedanolide.

New chiral auxiliaries based on the bicyclic-isoxazolidine skeleton, 3-oxa-2,7-diazabicylo[3,3,0]octane derivatives, were synthesized in 60–80% overall yields from amino acids. Asymmetric alkylation and boron aldol reaction using the auxiliaries proceeded with high selectivities. “Carboxylic amide” has been used for the asymmetric boron-mediated aldol reaction for the first time.

Asymmetric alkylation of the potassium enolates derived from N-propionyl benzopyrano-[4,3-c]-isoxazolidine derivatives with chiral alkyl triflates proceeded smoothly with high diastereoselectivity. The stereochemistry of the newly formed stereogenic center was fully controlled by the facial selectivity of the enolate according to the rule of double asymmetric synthesis. The application of this methodology led to the first synthesis of (+)-siphonarienone, a marine polypropionate natural product.

The asymmetric Horner-Emmons reaction of the phosphonate derived from a chiral benzopyrano-isoxazolidine (with 4-substituted cyclohexanones) proceeded in high diastereoselectivity with the aid of KHMDS and 18-crown-6 ether. Enantiomerically pure, axially dissymmetric cyclohexylidene alcohols, aldehydes and ketones were obtained from the diastereomerically pure Horner-Emmons products in a single step.

Treatment of chiral oxazolidinone with Bu 2 BOTf (2.5 equiv.) and Et 3 N (3.0 equiv.) quantitatively produced the doubly borylated enolate, which afforded the double aldol products with high diastereoselectivity after reaction with aldehydes.

New chiral auxiliaries based on the isoxazolidine skeleton have been developed. Characteristic feature of these auxiliaries are : 1) High reactivity for asymmetric alkylations. 2) Acylation of the auxiliary with an acid chloride and an amine, or DCC condensation. 3) One step transformation of the reaction products to the corresponding chiral alcohols, aldehydes and ketones without loss of the stereochemical integrity with the recovery of the auxiliary. Asymmetric alkylation of chiral β-substituted alkanols via their triflates lead to the easy access to the “reduced polypropionate units” as well as the first synthesis of the marine natural product (+) -siphonarienone. Enantiomerically pure axially dissymmetric cyclohexylidene compounds were synthesized using asymmetric Horner-Emmons reaction of the phosphonate derived from the auxilliary.

Benzopyrano[4,3-c]isoxazolidine derivatives, newly developed chiral auxiliaries for asymmetric alkylation, were synthesized and resolved in a unique manner. Resolution could be executed so efficiently that both enantiomers were obtained with a single resolving reagent in excellent yields.

The remarkable catalysis of Bu2SnO for nitrone formation in the nitrone-olefin cycloaddition reaction has been discovered, and has led to the development of a general method for the synthesis of N-unsubstituted isoxazolidine derivatives.

Asymmetric alkylation of the potassium enolates derived from N-propionyl benzopyrano-[4,3-c]-isoxazolidine derivatives with chiral alkyl triflates proceeded smoothly with high diastereoselectivity. The stereochemistry of the newly formed stereogenic center was fully controlled by the facial selectivity of the enolate according to the rule of double asymmetric synthesis. The application of this methodology led to the first synthesis of (+)-siphonarienone, a marine polypropionate natural product.

The asymmetric Horner-Emmons reaction of the phosphonate derived from a chiral benzopyrano-isoxazolidine (with 4-substituted cyclohexanones) proceeded in high diastereoselectivity with the aid of KHMDS and 18-crown-6 ether. Enantiomerically pure, axially dissymmetric cyclohexylidene alcohols, aldehydes and ketones were obtained from the diastereomerically pure Horner-Emmons products in a single step.

New chiral auxiliaries based on the bicyclic-isoxazolidine skeleton, 3-oxa-2,7-diazabicylo[3,3,0]octane derivatives, were synthesized in 60–80% overall yields from amino acids. Asymmetric alkylation and boron aldol reaction using the auxiliaries proceeded with high selectivities. “Carboxylic amide” has been used for the asymmetric boron-mediated aldol reaction for the first time.

A new chiral reagent for syn-selective aldol reactions has been developed based on the recent finding that the stereochemistry of the boron-mediated aldol reaction of a carboxylic ester is controlled by the bulkiness of the alcohol moiety of the ester, by the proper choice of reagents, and by the enolization conditions. This readily available, inexpensive reagent has been utilized in studies directed towards the synthesis of the macrolide tedanolide.

The synthesis of BMPD, 1,3-bis(2-methylferrocenyl)propane-1,3-dione, was achieved via the Claisen condensation of a homochiral ferrocenecarboxylate and an acetylferrocene derived from the same chiral formylferrocene. Several metal complexes were prepared to exemplify the complexation ability of BMPD. A BMPD-yttrium complex was found to act as a new catalyst for silylcyanation of aldehydes with remarkable efficiency. As little as 0.2 mol% of the complex catalyzed the reaction of benzaldehyde and cyanotrimethylsilane to afford the cyanohydrin in 95% yield with 87% ee.

Bis-oxazolines (1–7) prepared from diethyl malonate and chiral amino alcohols were converted into their Cu(II) complexes which, upon activation, exhibit high enantioselectivity of up to 99 %ee for catalytic cyclopropanation of olefins.

Pdr5p in Saccharomyces cerevisiae is a functional homologue of mammalian P-glycoprotein implicated in multidrug resistance (MDR). In order to obtain useful inhibitors to overcome MDR in clinical tumors, screening of Pdr5p inhibitors has been carried out. We isolated a fungal strain producing Pdr5p inhibitors using our original assay system, and it was classified as Trichoderma sp. P24-3. The purified inhibitor was identified as isonitrile, 3-(3'-isocyano-cyclopent-2'-enylidene)-propionic acid, a compound whose carboxyl residue is essential for the inhibitory activity. A non-toxic concentration of the isonitrile (41.5 microg/ml, 255 microM) inhibited Pdr5p-mediated efflux of cycloheximide or cerulenin in Pdr5p-overexpressing cells. In addition, addition of the isonitrile led to accumulation of rhodamine 6G, a substrate of Pdr5p, in the Pdr5p-overexpressing cells. The inhibitory profiles of the isonitrile against S1360 mutants (S1360A and S1360F) of Pdr5p were different from those of FK506 and enniatin. The isonitrile did not influence PDR5 gene expression and the amount of Pdr5 protein, nor did it inhibit the function of Snq2p, a homologue of Pdr5p. Interestingly, the isonitrile inhibited the function of Cdr1p and Cdr2p, Pdr5p homologues in pathogenic yeast Candida albicans. Thus, it was found that the isonitrile shows a different inhibitory spectrum from that of FK506 and enniatin as a potent inhibitor for Pdr5p, Cdr1p, and Cdr2p.

Boron-mediated aldol reaction of carboxylic esters is described in detail. Contrary to the gener-al belief that carboxylic esters are inert toward the conventional enolization conditions, propionate esters are shqwn to have adequate reactivity on the boron-mediated aldol reaction. More impor-tantly, the stereochemical course of the aldol reaction can be controlled by the judicious choice of the enolization reagents. Complementary anti- and syn-selective asymmetric aldol reaction of structurally related chiral esters are developed. Also, novel double aldol reaction is discovered with acetate esters, which provides a precursor to the synthesis of chiral triols of C3-symmetry. Extensive NMR experiments lead to characterize the first carbon-bound boron enolates and the novel doubly borylate enolates as intermediates of the double aldol reaction. A plausible mecha-nism of the double aldol reaction is proposed.

(2S,3R)-2,4-Dimethyl-1,3-pentanediol R 2(N-Benzyl-N-mesitylenesulfonyl)amino-1-phenyl-1-propyl propionate Is this (+)-1 I (1′R)-Phenyl-(2′S)-[(phenylmethyl)[(2,4,6-trimethylphenyl)sulfonyl]amino-propyl(3R)-hydroxy-(2R),4-dimethylpentanoate 2 R (2S,3R)-2,4-Dimethyl-1,3-pentanediol 3 2-(N-Benzyl-N-mesitylenesulfonyl)amino-1-phenyl-propanol Keywords: stereoselective reactions, enantioselective; stereoselective reactions, diastereoselective; alkylation, C-alkylation (including Aldol, Michael, and Friedel-Crafts reactions); metal-catalyzed reactions (exclusive of reductions); reduction, CO2RCH2OH; alkylation N-alkylation

2-(N-Benzyl-N-mesitylenesulfonyl) amino-1-phenyl-1-propyl propionate R (−)-Norephedrine I 2-(N-mesitylenesulfonyl)amino-1-phenyl-1-propanol 2 2-(N-Benzyl-N-mesitylenesulfonyl)amino-1-phenyl-1-propanol 3 P 2-(N-Benzyl-N-mesitylenesulfonyl)amino-1-phenyl-1-propyl propionate 1 Keywords: sulfur compounds; alcohols and diols, substituted; sulfonation, N-sulfonation; acylation (including formylation and Friedel-Crafts reactions); alcohols and diols, substituted

The boron-mediated aldol reaction of carboxylic esters is described in detail. Contrary to the general belief that carboxylic esters are inert under the condition of the boron enolate formation, propionate esters are enolized with certain combinations of a boron triflate and an amine. More importantly, the stereochemical course of the aldol reaction can be controlled by the judicious selection of the enolization reagents. Treatment of propionate esters with c-Hex2BOTf and triethylamine produces anti-aldol products, and that with Bu2BOTf and diisopropylethylamine gives syn-aldol products selectively after reaction with aldehydes. Complementary anti- and syn-selective asymmetric aldol reactions with structurally related, readily available chiral norephedrine-derived propionate esters are developed.

By the Cu(II)-catalyzed reaction of 2-(4-diazo-3-oxoalkyl)pyridines (2), 4-alkoxycarbonyl (or 4-acyl)-3-oxo-1,2,3,4-tetrahydroquinolizinium ylides (3) were obtained in high yields. From the cycloaddition reaction of 3 with acetylenic esters (propynoates or acetylenedicarboxylates) the labile [2 + 3] cycloadducts, 3-oxo-3H-2a,4,5,8a-tetrahydropyrrolo[2,1,5-de]quinolizine-2a-carboxylates (8 or 12), were identified, which further reacted with DMAD (dimethyl acetylenedicarboxylate) to afford azocine derivatives (15 or 16) and produced pyrrolodihydroquinolizines (9 or 20) by dealkoxycarbonylation.

The remarkable catalysis of Bu2SnO for nitrone formation in the nitrone-olefin cycloaddition reaction has been discovered, and has led to the development of a general method for the synthesis of N-unsubstituted isoxazolidine derivatives.

The use of NaBH4-H2SO4, For the reduction of α-amino acids to the corresponding aminoalcohols offers definite advantages: i) operational simplicity, ii) ease of scaling up the reaction without risking explosion, and iii) use of the inexpensive reagents.

The first total synthesis of (±)-aplysin-20 involving 16 steps from nerolidol in a 10% overall yield is described.