Total Synthesis of Bryostatin 16 Trost

8 Steps Including (TiCI2(0-/-P r)a) catalyzed vinylogous aldol addition and hydroxy directed reduction of C3 ketone using Me4NB(OAc)3H 

As practiced in the preceding syntheses by Evans and Nishiyama and Yamamura, the A-ring fragment 43 is formed through substrate-directed vinylogous aldol reaction of the Brassard-type diene 19 and the chiral aldehyde 42, which is prepared using Brown s protocols for enantioselective allylation [53], followed by hydroxy-directed nnn-diastereoselective reduction of the C3 ketone (Me4NB(OAc)3H) [41], 

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