78c o o phenylselenolactonization 140 o otbs h 141

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Unformatted text preview: ctone –  135 introduced by SN2’ ­an7 opening of 136 M THPO I 135 + H –  Leads to 134 136 H C-C bond formation H 134 •  Lef ­hand side: iniFaFng terminus for tandem radical cyclizaFon •  Right ­hand side: cascade terminator Nicolaou, Classics in Total Synthesis, 1996 11 Total Synthesis of hirsutene OH O OAc 1.) NaBH4, CeCl3 2.) Ac2O, Et3N 132: 2-methylcyclpentenone 138-racemic Luche Reduction LDA, THF, 78C OLi (Ireland ester enolate Claisen rearrangement) OTBS H O CHCl3, reflux O then t-BuMe2SiCl, HMPA OTBS 140 γ,δ ­unsaturated tert ­butyldimethylsilyl ester 139: silyl ketene acetal OTBS 2' 1' O 1 1' 5 2 3 4 139: silyl ketene acetal 4 H 5 = 2' TBSO O O 3 1 2 H 140: γ,δ ­unsaturated tert ­butyldimethylsilyl ester Nicolaou, Classics in Total S...
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This document was uploaded on 03/01/2014 for the course CEM 852 at Michigan State University.

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