Tandem Beckmann and Huisgen-White rearrangement as an alternative to the Baeyer-Villiger oxidation of the bicyclo[3.3.1]nonane system: First asymmetric synthesis of (-)-dihydropalustramic acid. X-Ray molecular structure of 2β-ethyl-9-phenylsulfonyl-9-azabicyclo[3.3.1]nonan-3-one
The transformation of the 'fork head ketone' 3b into the corresponding bicyclic lactone 13 via the Beckmann followed by the Huisgen-White rearrangement is described. Application of the method to a homochiral 2-ethyl-substituted bicyclic ketone (+)-3dα gave efficiently (-)-dihydropalustramic acid (-)-2a, a degradation product from the alkaloid palustrine 1, in good optical yield.
Muraoka, Osamu,Zheng, Bao-Zhong,Okumura, Kazuhito,Tanabe, Genzoh,Momose, Takefumi,Eugster, Conrad Hans
p. 1567 - 1575
(2007/10/03)
The Norrish Type I Photo-cleavage of (+)-2β-Ethyl-9-azabicyclononan-3-one: A Short, Enantioselective Formal Synthesis of (-)-Indolizidine 223AB
The enantioselective alkylation of the "fork head ketone" (1) followed by the Norrish Type I photo-cleavage provided the short enantioselective synthesis of (-)-indolizidine 223 AB (4).