CYCLISATION PROCESS FOR PREPARING 11 BETA-AXIALLY-SUBSTITUTED STEROIDS

摘要

There are disclosed substrates of the formula: (I) wherein: (a) R1 is H or C1-C4 alkyl; (b) R2 is H or C1-C4 alkyl with the proviso that R1 is H when R2 is alkyl, and with the proviso that R2 is H when R1 is alkyl; (c) R3 is a leaving group including hydroxy, C1-C4 alkoxy, C2-C4 alkoxalkoxy, C1-C7 acyloxy, and trialkylsilyloxy of less than fifteen carbons; and (d) R5(1) and R5(2) are each H, C1-C8 alkyl, or an optionally esterified or etherified hydroxy group including hydroxy, C1-C4 alkoxy, C2-C4 alkoxyalkoxy, C1-C15 trialkylsilyloxy, C4-C8 cycloalkoxy, C1-C7 carboxyacyloxy, or unsubstituted heterocyclic ether of five to seven members, with the proviso that at least one of R5(1) and R5(2) is hydrogen. A method is disclosed for the cyclization of the compounds of formula I leading to compounds of the following formulae: +TR having R4 as defined above, with R5 being R5(1) or R5(2) as defined above, and R7 being C1-C4 alkyl.