341032-13-1Relevant articles and documents
1-Oxaspiro[4.4]nonan-6-ones. Synthetic access via oxonium ion technology, optical resolution, and conversion into enantiopure spirocyclic α,β-butenolides
Paquette,Owen,Bibart,Seekamp,Kahane,Lanter,Corral
, p. 2828 - 2834 (2001)
A general approach to the synthesis of enantiomerically pure spirocyclic α,β-butenolides is presented where the fundamental framework is rapidly elaborated by acid- or bromonium ion-induced rearrangement of the carbinol derived by addition of 2-lithio-4,5-dihydrofuran to cyclobutanone. Subsequent resolution of the resulting ketones by either sulfoximine or mandelate acetal technology has been applied effectively. The availability of these building blocks makes possible in turn the acquisition of the enantiomers of dihydrofurans typified by 17, 35, and 38 and lactones such as 25 and 31, as well as the targeted title compounds. Complementary reductions of the early intermediates provide the added advantage that the α- and β-stereoisomeric carbinol series can be obtained on demand. These capabilities have been coordinated to allow the crafting of any member of the series in relatively few steps.
Bronsted acid catalyzed enantioselective semipinacol rearrangement for the synthesis of chiral spiroethers
Zhang, Qing-Wei,Fan, Chun-An,Zhang, Hai-Jun,Tu, Yong-Qiang,Zhao, Yu-Ming,Gu, Peiming,Chen, Zhi-Min
supporting information; experimental part, p. 8572 - 8574 (2009/12/29)
A new twist: The catalytic asymmetric semipinacol rearrangement reaction of 2oxo allylic alcohols 1 in the presence of a catalytic amount of chiral phosphoric acid (R)-2a or its silver salt (R)-2b affords enantiomerically pure spiroethers 3.
