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A highly enantioselective and practical synthesis of the HIV-1 reverse transcriptase inhibitor efavirenz (1) is described. The synthesis proceeds in 62% overall yield in seven steps from 4-chloroaniline (6) to give efavirenz (1) in excellent chemical and optical purity. A novel, enantioselective addition of Li-cyclopropyl acetylide (4a) to p-methoxybenzyl-protected ketoaniline 3a mediated by (1R,2S)-N-pyrrolidinylnorephedrine lithium alkoxide (5a) establishes the stereogenic center in the target with a remarkable level of stereocontrol.

Isoxazolidines have been synthesized in diastereomeric excess up to 94% via a MgBr2-induced chelation-controlled 1,3-dipolar cycloaddition reaction with N-hydroxyphenylglycinol as a chiral auxiliary. The diastereomerically pure isoxazolidines were further transformed into cyclic and acyclic beta-amino acid derivatives.

Synthese du compose du titre et de l'hydroxy-1 vinyl-8 benzo [d] naphto [1,2-b] pyrannone-6 a partir de la condensation de Pechmann du naphtalenediol-1,8 et d'ethyl-5 oxo-2 cyclohexanecarboxylate de methyle

BF3-catalyzed rearrangement of the bridged oxim (I) produces the azocine (II) as the only product.