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Stereocontrolled Photooxygenations–A Valuable Synthetic Tool §
Author(s) -
Adam Waldemar,
SahaMöller Chantu R.,
Schambony Simon B.,
Schmid Katharina S.,
Wirth Thomas
Publication year - 1999
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1999.tb08241.x
Subject(s) - computational biology , computer science , biochemical engineering , biology , engineering
The stereochemical course of the singlet‐oxygen ene reaction with acyclic olefins may be controlled if in the substrate conformational fixation (1,3‐allylic strain) an allyl‐ic substituent for interaction with the attacking oxygen enophile aligns. Various substrates were chosen to elucidate the features of the olefin that are necessary to control the sense ( threo versus erythro ) and the extent of the ii‐facial preference of the singlet‐oxygen attack. Depending on the electronic properties of the double bond and the nature of the allylic substituent, threo or erythro selectivity may be imposed through hydrogen bonding, electrostatic and steric effects and stereoelectronic alignment. Such directing properties, especially that of the hydroxy group, were also confirmed in the other reaction modes of singlet oxygen, namely the [4+2] cycloaddition to chiral naphthylenic alcohols and the [2+2] cycloaddition to an adamantylidene‐substituted allylic alcohol. The syntheses of the natural products Merucathin and Iso‐dihydromahubanolide B are two examples in which such stereocontrolled photooxygenations have been used as key steps to build up the required chirality diastereose‐lectively.