X = Y - ZH systems as potential 1,3-dipoles part 35. Generation of nitrones from oximes. Class 3 processes. Tandem intramolecular michael addition (1,3-azaprotio cyclotransfer) - intermolecular 1,3-dipolar cycloaddition reactions.
摘要:
Aldoximes and ketoximes possessing gamma- or delta-alkenyl substituents undergo thermal conversion to 5- and 6- membered cyclic nitrones via a 1,3-azaprotio cyclotransfer, a 2n + 2-sigma + 2-pi concerted process, rather than a Michael addition. The reactions can be performed as a tandem nitrone formation-cycloaddition sequence or, if required, the intermediate nitrones can be isolated. The cycloadditions usually proceed via an exo-transition state and show both regio- and diastereofacial-specificity. Preliminary attempts at chiral induction via a menthyl auxiliary are reported.
作者:Xuan B. Nguyen、Yuji Nakano、Nisharnthi M. Duggan、Lydia Scott、Martin Breugst、David W. Lupton
DOI:10.1002/anie.201905475
日期:2019.8.12
Direct polarity inversion of conjugate acceptors provides a valuable entry to homoenolates. N‐heterocyclic carbene (NHC) catalyzed reactions, in which β‐unsubstituted conjugate acceptors undergo homoenolate formation and C−C bond formation twice, have been developed. Specifically, the all‐carbon (5+1) annulations give a range of mono‐ and bicyclic cyclohexanones (31 examples). In the first family of
X = Y - ZH systems as potential 1,3-dipoles part 35. Generation of nitrones from oximes. Class 3 processes. Tandem intramolecular michael addition (1,3-azaprotio cyclotransfer) - intermolecular 1,3-dipolar cycloaddition reactions.
作者:Ronald Grigg、Jasothara Markandu、Trevor Perrior、Sivagnanasundram Surendrakumar、William J. Warnock
DOI:10.1016/s0040-4020(01)89883-5
日期:1992.1
Aldoximes and ketoximes possessing gamma- or delta-alkenyl substituents undergo thermal conversion to 5- and 6- membered cyclic nitrones via a 1,3-azaprotio cyclotransfer, a 2n + 2-sigma + 2-pi concerted process, rather than a Michael addition. The reactions can be performed as a tandem nitrone formation-cycloaddition sequence or, if required, the intermediate nitrones can be isolated. The cycloadditions usually proceed via an exo-transition state and show both regio- and diastereofacial-specificity. Preliminary attempts at chiral induction via a menthyl auxiliary are reported.