A novel synthesis oftrans-enynes from substituted tetrahydropyrans
作者:Burhan Karadogan、Neil Edwards、Philip J. Parsons
DOI:10.1016/s0040-4039(99)01176-4
日期:1999.8
A novel method for the synthesis oftrans-enynes is described, which relies on a butyllithium induced ring scission of 3-bromo-2-ethynyltetrahydropyrans.
The stericcourse of some reactions of 2,3-dihalotetrahydropyrans with sodium methoxide and with methyl- and phenyl-magnesium bromides has been reinvestigated. Whereas the methanolysis of the - and -dichlorides occurs with practically complete inversion, it has been confirmed that their reactions, as well as those of the dibromides, with methyl-magnesium bromide are non-stereospecific, yielding mixtures
作者:Richard C. Brandon、John M. Derfer、Cecil E. Boord
DOI:10.1021/ja01161a069
日期:1950.5
Crombie, Leslie; Wyvill, Robert D., Journal of the Chemical Society. Perkin transactions I, 1985, p. 1971 - 1982
作者:Crombie, Leslie、Wyvill, Robert D.
DOI:——
日期:——
Stereoselective cyclisation of the 2-allyloxytetrahydropyran-3-yl radical and related species: The influence of anomeric effects
作者:Athelstan L.J. Beckwith、Dennis M. Page
DOI:10.1016/s0040-4020(98)01137-5
日期:1999.3
Ring closures of the 2-allyloxytetrahydropyran-3-yl radical 1b, its mono-oxa analog 1d and the all carbon system 1a give mainly the cis-fused syn-substituted bicyclononylcarbinyl radicals 2b, 2d and 2a, but the mono-oxa radical 1c gives mainly the cis-fused anti-substituted radical 3c. Molecular mechanics calculations show that the unexpected failure of the dioxa radical 1b to reflect the influence of the anomeric effect on the stereochemistry of cyclisation arises from the loss of one stabilising anomeric interaction in the conversion of the conformer 17 into either of the transition structures 16 or 19. (C) 1999 Elsevier Science Ltd. All rights reserved.