Lizeng Peng

L-Proline catalyzed asymmetric aldol reactions of protected hydroxyacetone

We extended the proline-catalyzed asymmetric direct aldol reactions to the TBDMS protected hydroxyacetone. This important donor provides a ready access to optically active monoprotected 1,2-diol units simultaneously accompanied by stereoselective carbon-carbon bond formation in 40–90% yield and in up to 95% ee.

First total synthesis and absolute configuration of marine cembrane diterpenoid (+)-11,12-epoxysarcophytol A

A concise and efficient total synthesis of (+)-11,12-epoxysarcophytol A (1), an epoxy cembrane diterpenoid from marine soft coral Lobophytum, is described, which allows the assignment of an absolute configuration (11S,12S) of the epoxide function unambiguously.

Studies on novel macrocyclization methods of cembrane-type diterpenoids: a Stille cyclization approach to (±)-isocembrene

Abstract An efficient total synthesis of (±)-isocembrene via an intramolecular Stille cross-coupling reaction is described. A novel strategy towards the 1,3-diene-based cembrane-type macrocyclic diterpenoids has been realized.

Novel construction of the brassinolide side chain

Abstract A stereoselective synthesis of brassinolide, which involves construction of the side chain by a highly stereoselective aldol reaction between 20 S -6β-methoxy-3α,5- cyclo -5α-pregnane-20-carboxaldehyde 2 and ketone 3 or 4 catalyzed by l -proline, is described.

A concise and stereoselective synthesis of the brassinolide and related compounds’ side chains

A stereoselective synthesis of brassinolide, which involves construction of the side chain by highly stereoselective aldol reaction of 20S-6β-methoxy-3α,5-cyclo-5α-pregnane-20-carboxadehyde 5 with the anion of α-silyloxy ketone 6 is described.

HIGHLY STEREOSELECTIVE SYNTHESIS OF NERYLGERANIOL-18-OIC ACID

A stereoselectively total synthesis of nerylgeraniol-18-oic acid from geraniol was described. The key steps were the iodization- rearrangement of 2, 3-epoxy alcohol 4, stereoselective Claisen rearrangement and Horner-Emmons olefination reaction.

Enantioselective total synthesis of natural 11,12-epoxycembrene-C

Abstract The first enantioselective total synthesis of (+)-11,12-epoxycembrene-C (1), a novel naturally occurring cembranoxide isolated from tropical marine soft coral, was achieved via a general approach by employing an intramolecular McMurry coupling and Sharpless asymmetric epoxidation as key steps from readily available starting materials.

First enantioselective total synthesis of (natural) (+)-11,12-epoxy-11,12-dihydrocembrene-C and (−)-7,8-epoxy-7,8-dihydrocembrene-C

The first enantioselective total syntheses of (+)-11,12-epoxy-11,12-dihydrocembrene-C 1 and (−)-7,8-epoxy-7,8-dihydrocembrene-C 2, two naturally occurring cembranoxides isolated from tropical marine soft corals, are achieved via a general approach by employing an intramolecular McMurry coupling and Sharpless asymmetric epoxidation as key steps from readily available starting materials. The syntheses presented here verify the absolute stereochemistry assignment of 1 as (11S,12S) by Bowden et al. two decades ago, and the epoxy configuration of 2 was assumed as (7R,8R) accordingly.

SYNTHESIS OF PYRAZOLE DERIVATIVES 4(1H)-QUINOLONE AND 4-CHLOROQUINOLINE BY THERMOLYSIS OF ARYLAMINOMETHYLENE MELDRUM's ACID DERIVATIVE

ABSTRACT Efficient syntheses of 4(1H)-quinolone 1 and 4-chloroquinoline 2 by thermolysis of arylaminomethylene Meldrums acid derivative starting from 2-nitrophenyl acetic acid.

Syn-anti epimerization of aldols by aldolate dianions

A proposed mechanism based on distal aldolate dianions is illustrated in this paper to explain the outcome of the directed aldol reaction when one uses more than 2 equivalents of base.