Rhodium-Catalyzed Cyclization of O,ω-Unsaturated Alkoxyamines: Formation of Oxygen-Containing Heterocycles.

O,ω-Unsaturated N-tosyl alkoxyamines undergo unexpected RhIII -catalyzed intramolecular cyclization by oxyamination to produce oxygen-containing heterocycles. Mechanistic studies show that an aziridine intermediate seems to be responsible for the formation of the heterocycles, possibly via a RhV species.

Synthesis of the Acyclic Carbon Skeleton of Filipin III.

The synthesis of the carbon skeleton of filipin III, a polyenic macrolactone possessing 11 stereogenic centers, was achieved using a convergent strategy with the longest linear sequence of 19 steps starting from hexanal. Construction of the polyene was realized using two successive Heck couplings as the key steps. Control of the stereogenic centers of the polyol fragment was performed by utilizing an Evans aldolization, a 1,3-syn aldolization, enantio- and diastereoselective allylations, a hemiacetalization/oxa-Michael sequence, and a 1,3-syn reduction. The polyol and polyenic fragments were coupled using a 1,5-anti diastereoselective aldolization followed by a 1,3-anti reduction.

Total Synthesis of (+)-Cryptocaryol A Using a Prins Cyclization/Reductive Cleavage Sequence.

The total synthesis of (+)-cryptocaryol A was achieved in 20 steps from (R)-glycidol. The key steps were a Prins cyclization/reductive cleavage sequence to construct the C5-C11 polyol fragment, a diastereoselective aldol reaction to control the stereogenic center at C13, and a stereocontrolled reduction to introduce the stereogenic center at C15.

Synthetic approach to wortmannilactone C.

A diastereomer of wortmannilactone C has been synthesized according to a convergent and versatile strategy from tert-butyl 3-hydroxypropanoate and ethyl (R)-3-hydroxybutanoate. The key steps are a Liebeskind cross-coupling and a Horner-Wadsworth-Emmons (HWE) reaction to construct the macrolactone. The stereogenic centers at C9, C11, and C21 were controlled by enantioselective allyltitanations, and the C19 stereocenter was controlled by using a Noyori reduction of an acetylenic ketone.

Diastereo- and enantioselective synthesis of 1,3,5,7-tetraol structural units using a Prins cyclisation-reductive cleavage sequence.

Stereocontrolled and efficient access to all the diastereomers of 1,3,5,7-tetraol structural units was developed using a Prins cyclisation-reductive cleavage sequence applied to tetrahydropyran aldehydes. Furthermore, these tetraols can be selectively functionalized.

Rhodium(III)-catalyzed allylic C-H bond amination. Synthesis of cyclic amines from ω-unsaturated N-sulfonylamines.

For the first time, intramolecular allylic amination was conducted using rhodium(III) according to an "inner-sphere" type mechanism with amines activated by only one electron-withdrawing group. The activation of C(sp(3))-H bonds was chemoselective and allows the access to a variety of substituted cyclic amines such as pyrrolidines and piperidines.

Stereoselective synthesis of conjugated trienols from allylic alcohols and 1-iodo-1,3-dienes.

The stereoselective synthesis of conjugated trienes has been achieved from allylic alcohols and 1-iodo-1,3-dienes using Pd(OAc)(2)/AgOAc.

Synthesis and evaluation of new polyenic compounds as potential PPARs modulators.

In order to identify new leads for the treatment of type 2 diabetes, polyenic molecules A and B derived from nipecotic acid and dienol derivatives C have been prepared and their effect on PPARs transcriptional activity evaluated and compared to that of rosiglitazone, WY14,643 and GW501516. Among the synthesized compounds, dienol 39 is the most active, increasing WY14,643 PPARα response and demonstrating partial agonist properties on rosiglitazone PPARγ.

Mild nonepimerizing N-alkylation of amines by alcohols without transition metals.

A one-pot two-step sequence involving an oxidation/imine-iminium formation/reduction allowed the N-alkylation of amines by alcohols without any epimerization when optically active alcohols and amines are involved in the process.

Synthesis of the monomeric counterpart of marinomycin A.

An efficient and highly convergent synthesis of the monomeric counterpart of the antitumor-antibiotic marine natural product marinomycin A was achieved by using optically active titanium complexes to control the configuration of the stereogenic centers, a highly stereo- and regioselective cross-metathesis to generate the (E)-configured C20-C21 double bond, and a Horner-Wadsworth-Emmons olefination followed by a Pd-catalyzed Stille cross-coupling to construct the tetraene moiety.

A versatile route to the tulearin class of macrolactones: synthesis of a stereoisomer of tulearin A.

A versatile synthetic approach to the tulearin class of macrolactones has been developed and deployed to make a stereoisomer of tulearin A. The knowledge gained about structure and synthesis will expedite the assignment of the stereostructure of this new anticancer agent.

Diastereodivergent addition of allenylzincs to aryl glyoxylates.

A diastereodivergent addition of allenylzincs to aryl glyoxylates was observed depending on the method used for the preparation of the allenylzinc reagent. The allenylzincs were prepared from propargylic benzoates in the presence of a palladium catalyst or by metalation of alkynes.

Synthesis of two bioactive natural products: FR252921 and pseudotrienic acid B.

Concise and highly convergent syntheses of the immunosuppressive agent FR252921 and the related antimicrobial natural product pseudotrienic acid B were achieved from a common intermediate by using optically active titanium complexes to control the configuration of the stereogenic centers, a highly stereo- and regioselective cross-metathesis to generate the triene moieties, and a Stille cross-coupling to install the dienic units.

Synthesis of a promising immunosuppressant: FR252921.

A concise and highly convergent synthesis of the promising immunosuppressant FR252921 was achieved by using optically active titanium complexes to control the configuration of the three stereogenic centers.

An efficient and stereoselective synthesis of the monomeric counterpart of marinomycin A.

[structure: see text] The monomeric counterpart of marinomycin A, an antitumor-antibiotic marine natural product, was synthesized efficiently in 11 steps from the commercially available ethyl (R)-(-)-3-hydroxybutyrate. The strategy was highlighted by a crucial regio- and stereoselective cross-metathesis to form the C20-C21 double bond, enantioselective allyltitanations to control the configuration of the C17, C23, and C25 stereogenic centers, and a stereocontrolled construction of the tetraene moiety based on an original Horner-Wadsworth-Emmons olefination followed by a Pd-catalyzed cross-coupling.

Total synthesis of herbimycin A.

[structure: see text] Hsp90 has recently emerged as a promising biological target for treatment of cancer. Herbimycin A and other members of the benzoquinoid ansamycin class of natural products are known to inhibit Hsp90 activity. The total synthesis of herbimycin A was achieved from the commercially available Roche ester 1 by using allylmetals to control the stereogenic centers at C6, C7, C10, C11, and C12 and a ring-closing metathesis to control the (Z)-double bond of the (E,Z)-dienic moiety.

Rearrangement of homoallylic alcohols induced by DAST.

[reaction: see text] Treatment of beta,gamma-unsaturated monoprotected 1,2-diols with diethylaminosulfur trifluoride (DAST) allows the stereoselective formation of beta,gamma-unsaturated aldehydes in good yields and with a good transfer of chirality.

Synthetic approaches and total synthesis of natural zoapatanol.

[structure: see text] The total synthesis of (+)-zoapatanol utilizing an intramolecular Horner-Wadsworth-Emmons olefination and an enantioselective Sharpless dihydroxylation as the key steps has been achieved. An advanced oxepene intermediate has been obtained by applying a ring-closing metathesis to an unsaturated enol ether.

Synthesis of omega-hydroxy ketones from omega-benzyloxy Weinreb amides by using a chemoselective nucleophilic addition/Birch reduction process.

[reaction: see text] A chemoselective nucleophilic addition/Birch reduction process applied to omega-benzyloxy Weinreb amides led to omega-hydroxy ketones in good yields.