A stereodivergent access to naturally occurring aminocarbasugars from (Phenylsulfonyl)-7 -oxa-bicyclo[2.2.1 ]heptane derivatives. Total synthesis of ( + )-Validamine and its CI and C2 stereoisomers

Abstract

The total syntheses of the antibiotic validamine an its three diastereomers have been

acomplished and their racemic penta-N-O-acetates via stereocontrolled nucleophilic epoxidation

of polihydroxylated cyclohexenyl sulfones, obtained from (phenylsulphonyl)-7-

oxabicyclo[2,2, l ]heptanes. The diastereoselectivity of the epoxidation can be readily

controlled by careful choice of the hydroxyl protecting group. Ring opening of the

resulting epoxisulfones followed by stereocontrolled introduction of an amine precursor

led to the four C-l and C-2 diastereomers of the I-aminocarbasugars.

La epoxidación nucleofilica estereocontrolada de ciclohexenil sulfonas polidroxiladas, obtenidas a partir de (fenilsulfonil)-7-oxabiciclo[2,2, l ] heptano s conduce a la síntesis total del antibiótico validarnina y sus tres diastereoisómeros. La diastereoselectividad de la epoxidación puede controlarse facilrnente mediante la elección del grupo protector del hidroxilo. La apertura del anillo de las epoxisulfonas resultantes, seguida de la introduc ción estereocontrolada de un precursor del grupo