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Pyrroles, privileged structural motifs in drug and material science, have been synthesized by indium(III)-catalyzed intramolecular cyclization of homopropargyl azides. This methodology exhibits a broad substrate scope, providing substituted pyrroles and bispyrroles in good yields. Furthermore, an atom-economical sequential method for the synthesis of benzo[g]indoles has been discovered from azido-diynes using InCl3as catalyst. The method involves two successive intramolecular indium-catalyzed 5-endo-digalkyne hydroamination and a hydroarylation reactions with 6-endo-digregioselectivity.

A series of donor–acceptor–acceptor (D–A–A) and donor–acceptor–donor (D–A–D) systems based on a pyrimidine π-spacer with various substituents at the C-2 position has been successfully prepared. The synthesis involved site-selective palladium cross-coupling reactions of chloropyrimidines with triorganoindium reagents and proceed in good yields and with atom economy. 4-(N,N-Diphenylamino)phenyl was chosen as the donor group and thien-2-yl dicyanovinylene as the acceptor one. The optical, vibrational, electrochemical, and density functional theory (DFT) calculations of these molecular systems were analyzed, and experimental values show the important role of the substituents at the C-2 position of the pyrimidine with stronger electron accepting ability, absorption in a wide range of UV/vis, acceptable fluorescence lifetime, and effective intramolecular charge transfer (ICT) properties. The ICT was observed in both series by the bathochromic shift on increasing the polarity of the solvent. In addition, DFT calculations found lower lowest unoccupied molecular orbitals of D–A–A molecules that suggest good electron ejection and transportation, being good properties for their application in various organic optoelectronic devices.

Triorganoindium reagents (R3In) react with tetrahydroisoquinolines (THIQs) in the presence of Ph3CBF4as an oxidant to afford 1-substituted THIQs. The reaction proceeds in good yields at rt using 50 mol % R3In with a variety of organic groups. 1H NMR studies show the generation of an iminium ion intermediate, supporting a two-step mechanism based on THIQ oxidation and R3In nucleophilic addition. This reaction was applied to the synthesis of the alkaloid nuciferine in three steps.

A new atom-economical synthesis of β-alkenyl-substituted BODIPYs via indium(III)-catalyzed intermolecular alkyne hydroarylation with meso-substituted BODIPYs is described. While catalysis with InI3allows the double β-functionalization of BODIPY, resulting in regioselectively branched β,β′-disubstituted alkenyl BODIPYs, catalytic InCl3enables the formation of linear β-substituted alkenyl BODIPYs. Subsequent In(III)-catalyzed intermolecular alkyne hydroarylation allows the synthesis of unsymmetrical push–pullBODIPY derivatives. Therefore, indium catalysis offers complementary regioselectivity in good chemical yields and functional group tolerance. The resulting BODIPY dyes displayed bathochromically shifted absorption and emission according to the electron-nature of the substituents in the alkenyl moiety with high molar extinction coefficients (ε up to 88,200 M–1cm–1) and quantum yields (0.14–0.96).

Indium(III) halides catalyze the hydroalkoxylation reaction of ortho-alkynylphenols to afford benzo[b]furans in good yields. The reaction proceeds with 5-endo-digregioselectivity with a variety of phenols functionalized at the arene and alkyne moieties in high yields using InI3(5 mol %) in DCE. Experimental and computational studies support a mechanism based on the indium(III) π-Lewis acid activation of the alkyne followed by nucleophilic addition of the phenol and final protodemetalation to afford the corresponding benzo[b]furan. DFT calculations suggest that dimer In2I6is the catalytic species through a novel double coordination with the alkyne and the hydroxyl group.

A novel rhodium‐catalyzed allylic substitution reaction using indium organometallics is reported. Aryl‐ and heteroarylindium reagents reacted in THF at 80 °C with primary and secondary allyl halides and their derivatives under rhodium(I) catalysis to afford the α‐substituted products in good yields and with high regio‐ and stereoselectivity. The reaction takes place with substoichiometric amounts of the triorganoindium reagents, which demonstrates the efficiency of the indium–rhodium transmetallation process in carbon–carbon bond‐forming reactions.

The palladium‐catalyzed cross‐coupling reaction of organogold(I) reagents (alkyl, alkenyl, aryl, and alkynyl) with organic electrophiles, such as aryl and alkenyl halides, aryl triflates, benzyl bromide, and benzoyl chloride is reported. The reaction takes place, under palladium catalysis, at room temperature with short reaction times to give the corresponding cross‐coupling products in high yields.

The first total synthesis of (+)‐neomarinone has been achieved by following a concise and convergent route using methyl (R)‐lactate and (R)‐3‐methylcyclohexanone as chiral building blocks. Key steps of the synthesis are the stereocontrolled formation of the two quaternary stereocenters by diastereoselective 1,4‐conjugate addition and enolate alkylation reactions, and the construction of the furanonaphthoquinone skeleton by regioselective Diels–Alder reaction between a 1,3‐bis(trimethylsilyloxy)‐1,3‐diene and a bromoquinone. The synthesis proves the relative and absolute stereochemistry of natural neomarinone.

The regio- and stereoselectivity of the palladium-catalysed cross-coupling reactions of indium organometallics withstereodefined 1-haloalkenes and 1,1-dihaloalkenes have been studied. Triorganoindium reagents (R3In; R = alkyl, alkenyl, aryl and alkynyl) can be stereospecifically coupled with stereodefined alkenyl iodides in good yields and short reaction times under palladium catalysis. Additionally, the palladium-catalysed cross-coupling reaction of R3In (90 mol-%) with 1,1-dibromo-1-alkenes gave dicoupling products in high yields. When the reaction was performed with 40 mol-% of aryl-, vinyl- and alkynylindium derivatives, trans-selective monosubstitution products were obtained in moderate to good yields. These selective couplings were performed with [Pd2dba3]/P(2-furyl)3 (1:1, 2 mol-%) at 0 °C or, for 1,1-dibromo-1-alkenes with an aromatic group in the β-position, [Pd(DPEPhos)Cl2] (2 mol-%) at room temperature as the catalytic system. The resulting (Z)-monobromoalkenes can be further functionalized by cross-coupling reaction with various R3In (R = alkyl, aryl and alkynyl) in the presence of [Pd(tBu3P)2] as catalyst, at room temperature, to provide trisubstituted olefins in good yields.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

The first enantioselective sp–sp3cross‐coupling reaction between alkynyl organometals and racemic benzyl bromides is reported. The coupling is performed at room temperature by using NiBr2⋅diglyme and (S)‐(iPr)‐Pybox as the catalytic system and trialkynylindium reagents as nucleophiles. The reaction is stereoconvergent, both enantiomers of the racemic benzyl bromide are converted into one enantiomer of the product, and stereospecific. The reaction takes place efficiently in good yields and with high atom economy, as the triorganoindium reagents transfer the three organic groups attached to indium (only 40 mol % of R3In is used).

Triorganoindium reagents (R3In) react with propargylic esters under palladium catalysis via an SN2‘ rearrangement to afford allenes in good yields and with high regioselectivity. The reaction proceeds smoothly at room temperature with a variety of R3In (aryl, alkenyl, alkynyl, and methyl). When chiral, nonracemic propargylic esters are employed, the reaction takes place with high anti-stereoselectivity providing allenes with high enantiomeric excess.

The stereoselectivity of the ultrasonically induced zinc—‐copper conjugate addition of iodides to chiral α,β‐unsaturated carbonyl systems under aqueous conditions was studied. Alkyl iodides add diastereoselectively to methylenedioxolanone 1and methyleneoxazolidinone 2to afford the 1,4‐addition products in good yields (38–95 %) and with high diastereomeric excess (44–90 % de). The 1,4‐addition to chiral γ,δ‐dioxolanyl‐α,β‐unsaturated esters 3–5also proceeds with good yields (51–99 %). The diastereoselectivity is dependent on the geometry of the olefin: the Zisomer 3gives high diastereoselectivity, while the reactions with the Eisomer 4are nonstereoselective. The reaction proceeds with excellent chemoselectivity and allows the use of iodides bearing ester, hydroxy, and amino groups. Since the 1,4‐addition products can be readily hydrolyzed, this methodology constitutes a novel entry for the enantioselective synthesis of α‐ and γ‐hydroxy acids and α‐amino acids in aqueous media. The results obtained support the radical mechanism proposed by Luche, and represent one of the few examples of a radical stereoselective conjugate addition in aqueous medium.

The stereoselectivity of the ultrasonically induced zinc—-copper conjugate addition of iodides to chiral α,β-unsaturated carbonyl systems under aqueous conditions was studied. Alkyl iodides add diastereoselectively to methylenedioxolanone 1 and methyleneoxazolidinone 2 to afford the 1,4-addition products in good yields (38–95 %) and with high diastereomeric excess (44–90 % de). The 1,4-addition to chiral γ,δ-dioxolanyl-α,β-unsaturated esters 3–5 also proceeds with good yields (51–99 %). The diastereoselectivity is dependent on the geometry of the olefin: the Z isomer 3 gives high diastereoselectivity, while the reactions with the E isomer 4 are nonstereoselective. The reaction proceeds with excellent chemoselectivity and allows the use of iodides bearing ester, hydroxy, and amino groups. Since the 1,4-addition products can be readily hydrolyzed, this methodology constitutes a novel entry for the enantioselective synthesis of α- and γ-hydroxy acids and α-amino acids in aqueous media. The results obtained support the radical mechanism proposed by Luche, and represent one of the few examples of a radical stereoselective conjugate addition in aqueous medium.

Vitamin D3 active metabolites 24R,25-(OH)2-D3, 24S,25-(OH)2-D3, and 1α,24R,25-(OH)3-D3 were synthesized by a convergent and stereoselective approach. In the synthetic route, the stereogenic center at C-24 was generated through ultrasonically induced aqueous conjugate addition of iodide 6 to Seebach's dioxolanone 5, and the vitamin D triene system was constructed using the Lythgoe approach. The synthesis, which is both short (seven steps from iodide 6) and efficient (32–40 % overall yield), allows the preparation of large quantities of the metabolites and provides a novel example of a highly stereoselective reaction promoted by the zinc-copper couple in aqueous media. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2111/2002/f3852_s.pdf or from the author.

Vitamin D3active metabolites 24R,25‐(OH)2‐D3, 24S,25‐(OH)2‐D3, and 1α,24R,25‐(OH)3‐D3were synthesized by a convergent and stereoselective approach. In the synthetic route, the stereogenic center at C‐24 was generated through ultrasonically induced aqueous conjugate addition of iodide 6to Seebach's dioxolanone 5, and the vitamin D triene system was constructed using the Lythgoe approach. The synthesis, which is both short (seven steps from iodide 6) and efficient (32–40 % overall yield), allows the preparation of large quantities of the metabolites and provides a novel example of a highly stereoselective reaction promoted by the zinc‐copper couple in aqueous media.

Vitamin D3and its hydroxylated metabolites are normally in thermal equilibrium with their previtamin D isomers. To evaluate the biologic activity of 1α,25‐dihydroxyprevitamin D3, we synthesized 19‐nor analogs of 1α,25‐dihydroxy(pre)vitamin D3because the absence of a C19methylene group prevents the isomerization of these analogs. The affinity of 1α,25‐(OH)2D3‐19‐nor‐D3for the intestinal vitamin D receptor and plasma vitamin D binding protein was mildly decreased [30 and 20% of the affinity of 1α,25‐(OH)2D3, respectively], but the affinity of 1α,25‐(OH)2‐19‐nor‐previtamin D3was only 1 and 6% of that of 1α,25‐(OH)2D3for the receptor and DBP, respectively. The in vitro effects on human promyeloid leukemia (HL‐60 cell) differentiation and osteocalcin secretion by human osteosarcoma (MG‐63) cells by 1α,25‐(OH)2‐19‐nor‐D3were nearly identical to those of 1α‐25‐(OH)2D3, whereas 19‐nor‐previtamin D3showed poor activity (2%). The in vivo calcemic effects of both analogs, studied in vitamin D‐deficient chicks treated for 10 consecutive days with the analogs, showed no activity of the previtamin D3analog and reduced calcemic effects (≤ 10%) of 1α,25‐(OH)2‐19‐nor‐D3. We conclude that the previtamin D form of 1α,25‐(OH)2D3has lost most of its biologic activity in vitro and in vivo.

In this paper we describe regioselective one-pot preparations of inner-outer-ring 1,3-bis[trimethylsilyloxy]dienes and their Diels-Alder reactions with electron-deficient dienophiles. The dienes were prepared in quantitative yield, and the Diels-Alder reactions proceeded smoothly, regioselectively and with good yields, allowing efficient construction of highly functionalized polycyclic skeletons such as naphthofurans, benzofurans and various carbocycles present in natural and non-natural products.

A series of semi-rigid analogues of the hormone 1α,25-dihydroxyvitamin D 3have been designed in order to study the topology required for binding to the hormone receptor (VDR). The new vitamin D 3analogues 2–5possess a rigid C17C20 bond and minimal structural modifications on the side-chain with respect to the hormone. Key steps for the introduction of the side-chains of the new analogues 2–5from hydrindanone 6involve a stereoselective Wittig reaction, olefin isomerization and dihalocyclopropanation.

The indium(III)-catalyzed cascade cycloisomerization reaction of 1,5-enynes with pendant aryl nucleophiles is reported. The reaction proceeds in cascade under mild reaction conditions, using InI3(5 mol %) as a catalyst with a range of 1,5-enynes furnished with aryl groups (phenyl and phenol) at alkene (Eand Z isomers) and with terminal and internal alkynes. Using 1-bromo-1,5-enynes, a one-pot sequential indium-catalyzed cycloisomerization and palladium-catalyzed cross-coupling with triorganoindium reagents were developed. The double cyclization is stereospecific and operates viaa biomimetic cascade cation-olefin through 1,5-enyne cyclization (6-endo-dig) and subsequent C–C hydroarylation or C–O phenoxycyclization. Density functional theory (DFT) computational studies on 1,5-enynyl aryl ethers support a two-step mechanism where the first stereoselective 1,5-enyne cyclization produces a nonclassical carbocation intermediate that evolves to the tricyclic reaction product through a SEAr mechanism. Using this approach, a variety of tricyclic heterocycles such as benzo[b]chromenes, phenanthridines, xanthenes, and spiroheterocyclic compounds are efficiently synthesized with high atom economy.

Multifold and sequential palladium-catalyzed cross-coupling reactions can be performed between triorganoindium compounds and oligohaloarenes using only a small excess of the organometallic reagent, low catalyst charge loading and short reaction times.

This method can also be applied to prepare other C‐6 substituted derivatives such as (VIb).

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

For Abstract see ChemInform Abstract in Full Text.

For Abstract see ChemInform Abstract in Full Text.