211503-91-2Relevant articles and documents
Stereoselective Conjugate Addition of the Lithium Anion of N-Allyl Imine to Unsaturated Esters: Application to the Enantiospecific Total Synthesis of (-)-Epibatidine
Prasad, Kavirayani R.,Uphade, Manoj B.
, p. 9648 - 9660 (2019)
A regio- and diastereoselective conjugate addition of the lithium anion of N-allyl imine (prepared from allylamine and benzophenone) to α,β-unsaturated esters in good yields is reported. The reaction was general and provided the γ-amino esters resulting from the regioselective C-C bond formation between the α-carbon to the nitrogen in the imine and the β-carbon of the unsaturated ester. Synthetic utility of the formed products was illustrated in the nonracemic total synthesis of the bioactive alkaloid (-)-epibatidine.
Synthesis of (-)-epibatidine
Evans, David A.,Scheidt, Karl A.,Downey, C. Wade
, p. 3009 - 3012 (2007/10/03)
matrix presented The synthesis of (-)-epibatidine has been accomplished utilizing a highly exo-selective asymmetric hetero Diels-Alder reaction. The key steps employed to transform the resulting bicycle into the natural product include a fluoride-promoted fragmentation and a Hofmann rearrangement.
Total synthesis of (-)-epibatidine using an asymmetric Diels-Alder reaction with a chiral n-acylnitroso dienophile
Aoyagi, Sakae,Tanaka, Ryuta,Naruse, Masaichi,Kibayashi, Chihiro
, p. 8397 - 8406 (2007/10/03)
An asymmetric total synthesis of (-)-epibatidine (1), isolated from the skin of the Ecuadorian poison frog, Epipedobates tricolor, of the family Dendrobatidae, has been achieved by virtue of the development of asymmetric hereto Diels-Alder (D-A) cycloaddition with an N-acylnitroso dienophile bearing the optically active 8-arylmenthol as a chiral source. Thus, in situ oxidation of the hydroxamic acid ent-12f incorporating the (1S,2R,5S)-8-(2- naphthyl)menthyl auxiliary was performed using the Swern conditions to produce the acylnitroso dienophile, which reacted at once with 2-chloro-5- (1,5-cyclohexadienyl)pyridine (7) to provide the (1S,4R)-meta-aza cycloadduct 24 as a major diastereoisomer. The observed facial diastereoselectivity is consistent with a transition-state model with the naphthyl group in 'stacked' position and with the acylnitroso group in the s-cis conformation, wherein π attractive interaction between the naphthyl and nitrosocarbonyl groups may contribute to facial control. Compound 24 underwent hydrogenation followed by removal of the chiral auxiliary with LiH2NBH3 and reductive cleavage of the N-O bond with Mo(CO)6 to give the amino alcohol derivative 29, which was converted to (-)-epibatidine via bromination followed by cyclization.
