966-47-2Relevant articles and documents
-
Pappo,R. et al.
, p. 1827 - 1830 (1973)
-
Organocatalytic asymmetric formation of steroids
Halskov, Kim Soholm,Donslund, Bjarke S.,Barfuesser, Sebastian,Jorgensen, Karl Anker
, p. 4137 - 4141 (2014)
A novel and simple one-step approach for the construction of optically active steroids in a highly stereoselective manner by using organocatalysis is presented. The reaction of (di)enals with cyclic dienophiles in the presence of a TMS-protected prolinol catalyst leads to the construction of important 14 β-steroids. This new reaction allows an easy access to optically active steroids with a variety of substituents in the A ring in high yields and up to greater than 99 % ee. The reaction has been extended to include the construction of B- and D-homosteroids as well as steroids containing heteroatoms in the B ring. The angular substituent at C13 can be varied and alkyl, ester, and sulfone functionalities are introduced with excellent stereoselectivities. Simple synthetic procedures provide access to a range of naturally occurring steroids such as estrone and related analogues. Organocatalysis made it possible: The reported methodology gives 14 β-steroids, displaying a broad generality, in one step, and includes various substituents on the A ring, variations of the B ring, hydroxy or alkyl substituents in the 12-position of the C ring, and different substituents in the angular position at C13. Furthermore, the developed reaction concept includes reactions with quinones to form D-homosteroids in excellent yields and stereoselectivities.
Catalytic asymmetric torgov cyclization: A concise total synthesis of (+)-estrone
Prevost, Sebastien,Dupre, Nathalie,Leutzsch, Markus,Wang, Qinggang,Wakchaure, Vijay,List, Benjamin
supporting information, p. 8770 - 8773 (2014/08/18)
An asymmetric Torgov cyclization, catalyzed by a novel, highly Bronsted acidic dinitro-substituted disulfonimide, is described. The reaction delivers the Torgov diene and various analogues with excellent yields and enantioselectivity. This method was applied in a very short synthesis of (+)-estrone.
Highly enantioselective [4 + 2] cycloaddition reactions catalyzed by a chiral N-methyl-oxazaborolidinium cation
Canales, Eda,Corey
supporting information; experimental part, p. 3271 - 3273 (2009/05/27)
(Chemical Equation Presented) The reaction of lithium aryl borohydrides with salts of β-amino alcohols provides a new route for the synthesis of oxazaborolidines. This method also leads to the first synthesis of hitherto elusive N-methyl oxazaborolidine c
