Total synthesis of the 6-silasteroid ring system

The total synthesis of the first¹ silasteroid ring system is described. A bidirectional construction was employed, starting from precursors of rings A and D. Metal-organic substitutions on dimethyldichlorosilane gave the allyl-m-methoxyphenyl derivative 2, as elements of rings AB. Hydroboration-oxidations led to the arylsilylpropionic acid 5. Activation and cyclization gave the key intermediate, 4,4 - dimethyl - 4 - sila - 6 - methoxy - 1 - tetralone, 7. Attachment of ring D and closure of ring C followed the Torgov-Smith outline, but required important differences in implementation, to give D,L-6, 6 - dimethyl - 6 - sila - 3 - methoxy - estra - 1,3,5(10),8,14 - pentaene - 17 - one, 11. Extensive physical data are presented.