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Radikalische Cyclisierung von Dienen, III Radikalische Cyclisierung von ( R )‐(‐)‐Carvon – Über den Einfluß von Charge‐Transfer‐Wechselwirkung auf den spezifischen Drehwert
Author(s) -
Weinges Klaus,
Maurer Wplfgang,
Reichert Hans,
Schilling Gerhard,
Oeser Thomas,
Iragartinger Hermann
Publication year - 1990
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19901230441
Subject(s) - chemistry , diastereomer , stereochemistry , hydrazone , stereoselectivity , electron transfer , medicinal chemistry , photochemistry , organic chemistry , catalysis
Radical‐Type Cyclisation of Dienes, 111. – Radical‐Type Cyclisation of ( R )‐( – )‐Carvone – On the Influence of Charge‐ Transfer Interactions on the Optical Rotation Under the conditions of radical cyclisation, a 1:1 diastereomeric mixture of (1R,2S,5R,R)‐(+)‐ ( 2a ) and (1R.2S,5R,6S)‐(+)‐6‐methoxy‐2,6‐dimethylbicyclo[3.2.1]octan‐3‐ones ( 2b ) is obtained from (R)‐(‐)‐carvone in 70% yield. the configuration fo 2a and 2b were confirmed by X‐ray structure analyses of their hydrazones 2d and 2e . The regio‐ and stereoselectivity of the radical cyclisation of 1 to 2a and 2b are discussed. The high value of the specific rotation [‐555] of 2d is traced back to charge‐transfer interactions between the endo ‐standing methoxy group at C‐6 as electron donor and the dinitrophenyl‐hydrazone group as electron acceptor.