“One-Pot” Reductive Lactone Alkylation Provides a Concise Asymmetric Synthesis of Chiral Isoprenoid Targets

An efficient method, based on nucleophilic addition to lactones followed by modified in situ Clemmensen reduction, provides a short synthetic route to chiral isoprenoid targets. The efficacy of this method has been exemplified through the synthesis of several targets including the commercial fragrance Rosaphen, the side chain of Zaragozic acid C, the cotton leaf sex pheromone, and the side chains of vitamin E

<i>N</i>-Acetylbornane-10,2-sultam: A Useful, Enantiomerically Pure Acetate Synthon for Asymmetric Aldol Reactions

N-Acetylbornane-10,2-sultam:  A Useful, Enantiomerically Pure Acetate Synthon for Asymmetric Aldol Reaction

Total Synthesis of 20-Norsalvinorin A. 1. Preparation of a Key Intermediate

The key tricylic intermediate 3a, for the total synthesis of the C20-nor analogue of salvinorin A, was prepared in seven steps from 3-furaldehyde. Key steps involved a highly regio- and diastereoselective Lewis acid assisted Diels−Alder reaction followed by base-promoted epimerization and a completely stereoselective conjugate reduction

Total Synthesis of 20-Norsalvinorin A. 1. Preparation of a Key Intermediate

The key tricylic intermediate 3a, for the total synthesis of the C20-nor analogue of salvinorin A, was prepared in seven steps from 3-furaldehyde. Key steps involved a highly regio- and diastereoselective Lewis acid assisted Diels−Alder reaction followed by base-promoted epimerization and a completely stereoselective conjugate reduction

Total Synthesis of 20-Norsalvinorin A. 1. Preparation of a Key Intermediate

The key tricylic intermediate 3a, for the total synthesis of the C20-nor analogue of salvinorin A, was prepared in seven steps from 3-furaldehyde. Key steps involved a highly regio- and diastereoselective Lewis acid assisted Diels−Alder reaction followed by base-promoted epimerization and a completely stereoselective conjugate reduction

A Mild Method for the Efficient [3,3]-Sigmatropic Rearrangement of <i>N,O</i>-Diacylhydroxylamines

A mild, general method for the [3,3]-sigmatropic rearrangement of N,O-diacylhydroxylamines, employing a combination of mild base and Lewis acid, is described. Employing stoichiometric amounts of reagents with respect to substrate provides α-acyloxyamides, whereas an excess of reagents favors formation of cyclic orthoamides

A Short Synthesis of the A/B Ring Systems of the Pacific Ciguatoxins P-CTX-3C and Dihydroxy-P-CTX-3C

A Short Synthesis of the A/B Ring Systems of the Pacific Ciguatoxins P-CTX-3C and Dihydroxy-P-CTX-3

Lewis Acid Catalyzed Diels−Alder Reactions of 1,2-Naphthoquinones

The use of BF3·OEt2 catalysis in Diels−Alder reactions of 3,4-unsubstituted 1,2-naphthoquinones provides direct access to cis-tetrahydrophenanthrene derivatives in good to excellent yields (66−99%) without rapid adduct aromatization commonly associated with corresponding thermal processes

A New Nucleophilic Addition/Ring-Closure Sequence. Enantioselective Synthesis of 3-Deoxy-8-oxatropanes

A study of new nucleophilic addition/ring-closure (NARC) sequences has resulted in the development of a stereoselective synthetic route to 3-deoxy-8-oxatropanes. The new sequences consisted of either a syn or anti aldol addition, employing an ω-alkenoyl sultam, followed by two-step bicyclic ring construction involving, consecutively, ring-closing metathesis and intramolecular oxymercuration

Remote Allylic Silyloxy Groups as Stereocontrol Elements in Intramolecular Oxymercurations of γ-Hydroxyalkenes

The diastereoselectivity in intramolecular oxymercurations of γ-hydroxyalkenes bearing a remote allylic oxy substituent has been investigated. It was found that the best selectivity was obtained by employing a combination of (Z)-alkene geometry and a tert-butyldiphenylsilyl protecting group attached to the remote allylic oxygen as in 4a−g. Cyclization, using mercuric acetate in dichloromethane, of all the (Z)-alkenols gave the syn diastereomer, 5a−g, as the major product. For example, cyclization of 4b gave syn diastereomer 5b and anti diastereomer 6b in a ratio of 7:1. It was found that this ratio could be improved by replacing dichloromethane with acetonitrile. Under these conditions the ratio of 5b to 6b increased to 19:1. Cyclization of (E)-alkene 9 gave very poor diastereoselection. These syn-selective intramolecular oxymercurations were exploited in enantioselective syntheses of two diastereomers of methyl nonactate