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Regio‐ and stereo‐controlled oxygen functionalization of cholesterol by photooxygenation in the presence of titanium tetraisopropoxide
Author(s) -
Adam Waldemar,
Staab Eugen
Publication year - 1988
Publication title -
liebigs annalen der chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0170-2041
DOI - 10.1002/jlac.198819880809
Subject(s) - photooxygenation , allylic rearrangement , chemistry , isomerization , surface modification , regioselectivity , alcohol , allyl alcohol , oxygen , photochemistry , titanium , singlet oxygen , medicinal chemistry , organic chemistry , catalysis
Abstract A convenient „one‐pot” procedure for the synthesis of the epoxy alcohols 1c and 2c by photooxygenation of cholesterol ( 1 ) in the presence of Ti(O i Pr) 4 was developed. The reaction proceeds regioselectively and stereospecifically. During the photooxygenation of 1 in the presence of Ti(IV) oxygen transfer 1a → 1c takes place much faster than the radical promoted isomerization 1a → 2a , thereby providing for regio‐control. In contrast to t BuOOH/Ti(O i Pr) 4 epoxidations of the allylic alcohols 1b and 2b , derived from the reduction of the allylic hydroperoxides 1a and 2a , no further oxidation products, e.g. the keto epoxy alcohol 1d , were observed under the „one‐pot” conditions.