Total synthesis of (+)-azimic acid, (+)-julifloridine, and proposed structure ofN-methyljulifloridine via cycloaddition of nitrone to a chiral dipolarophile

Regio- and diastereoselectivity of the 1,3-dipolar cycloaddition of α-aryl nitrone with methacrolein. A theoretical investigation

The mechanism, regio- and diastereoselectivity of the 1,3-dipolar cycloaddition of N-iso-propyl,α-(4-trifluoromethyl)-phenyl nitrone with methacrolein yielding the isoxazolidine cycloadduct has been studied at the B3LYP/6-31G(d) level of theory.

Asymmetric Synthesis of (+)-Iso-6-Cassine via Stereoselective Intramolecular Amidomercuration

The first asymmetric synthesis of (+)-iso-6-cassine is described. Lipase-catalyzed resolution, enantioselective Overman rearrangement, and diastereoselective intramolecular amidomercuration were used for the installation of the three stereocenters in (+)-iso-6-cassine, and cross-metathesis was employed for the attachment of the side-chain.

A Highly Stereoselective Synthesis of (−)-(ent)-Julifloridine from the Cyclization of an Alanine-Derived Chloroamine with an Acetylenic Sulfone

The cyclization of gamma-chloroamine 11, derived from l-alanine, and acetylenic sulfone 12 afforded the dehydropiperidine 19 via conjugate addition followed by intramolecular alkylation of the corresponding sulfone-stabilized anion. An unexpected acid-catalyzed desulfonylation of 19 occurred in one step via desilylation and tautomerization of the enamine moiety to the corresponding aldehyde, followed by elimination of p-toluenesulfinic acid. The highly stereoselective reduction of the resulting unsaturated aldehyde 25 with sodium cyanoborohydride produced piperidine 23 with a diastereomeric ratio of >98:2. (-)-(ent)-Julifloridine (8) was obtained by Swern oxidation of 23, followed by Wittig olefination and hydrogenation/debenzylation.