The synthesis of a sulfone containing analogue of the esperamicin-A(1) aglycone: A hetero Diels-Alder approach

The hetero Diels-Alder reaction of methyl/ethyl thiogly-oxylate, generated in situ from the corresponding anthracene adduct, with a series of dienes w as studied as a route to a key 3,4-dihydro-2H-thiopyran derivative bearing an acetylene function at C-2, and hydroxyl groups at C-3 and C-4. Such a mo lecule is a planned intermediate in the synthesis of a sulfone containing a nalogue of esperamicin-A(1). In this context, particular attention was dire cted to the hetero Diels-Alder reaction with polyfunctionalized dienes subs tituted at C-1 by a latent aldehyde function, and at C-4, C-2, and/or C-3 b y ether substituents.