Syn or an7 in tricyclic product i h h h h 1 hirustene

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Unformatted text preview: bonds formed –  2 conFguous stereogenic centers formed –  2 carbocyclic rings formed Nicolaou, Classics in Total Synthesis, 1996 9 Retrosynthetic Analysis and Strategy of hirsutene •  133132131 (5 ­exo ­radical cyclizaFon) –  Must proceed in a cis fashion H  TransiFon state to strained H 5-exo-dig H 131 5-exo-dig radical cyclization radical cyclization H H 132 H H 133 H trans ­fused bicyclo[3.3.0]octane does not permit overlap between SOMO and LUMO of the alkene. •  Side chains in monocyclic radical, 134 dictates 2 outer ring relaFonships. –  syn or an7 in tricyclic product I H H H H 1: hirustene H –  cis ­an7 ­cis ring fusion stereochemistry arises naturally from cyclizaFon precurser with trans ­disposed side chains. 10 134 Nicolaou, Classics in Total Synthesis, 1996 Retrosynthetic Analysis and Strategy of hirsutene •  trans ­DisubsFtuted cyclopentene, 134 retrosyntheFcally from –  Organmetallic reagent –  cis ­fused bicyclic la...
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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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