112661-57-1Relevant articles and documents
Structure-reactivity study of O-tosyl Cinchona alkaloids in their new synthesis and in hydrolysis to 9-epibases. Unexpected formation of cinchonicine enol tosylate accelerated by microwave activation
Lipinska, Teodozja M.,Piechocka, Katarzyna,Denisiuk, Monika,Chmiel, Beata,Skorska-Stania, Agnieszka
experimental part, p. 264 - 280 (2012/07/17)
New methods for O-tosylation of the natural Cinchona alkaloids have been discovered as a biphasic processes with Bu3N as a catalyst. The optimized excess of tosyl chloride, necessary for transformation of each of the four alkaloids into O-tosyl derivative, decreases in the following order: quinine, quinidine, cinchonidine and cinchonine. The same decreasing order has been noticed for the hydrolysis rate of the appropriate tosylates to 9-epibases. Difficult conversion of O-tosylcinchonine in the hydrolytic medium of aqueous tartaric acid gives 9-epicinchonine together with parallel formation of cinchonicine enol tosylate. The latter product is obtained as the main when both cinchonine and cinchonidine tosylates react in the presence of salicylic acid under controlled microwave heating. On the basis of X-ray structure of the new alkene product, the stereoselective syn-E2 quinuclidine ring opening process, competing to the SN2 hydrolysis is postulated for this transformation. ARKAT-USA, Inc.
Enantioselektive Katalyse, 106 9-Amino(9-deoxy)cinchona-Alkaloide und Deren Derivate
Brunner, H.,Buegler, J.
, p. 77 - 84 (2007/10/03)
The stereospecific formation of 9-amino(9-deoxy)cinchona alkaloids with the configuration of the corresponding natural products was achieved by a sequence of reactions, including a substitution with inversion of configuration. Thus, the corresponding epi-alkaloids were reacted with hydrazoic acid, triphenylphosphine and diisopropyl azodicarboxylate followed by an in situ reduction of the intermediary azides. The configurations of the products were established by CD- and 1H-NMR-spectroscopy. Several amide, imine and amine derivatives were prepared from these amino-substituted alkaloids. Their ability to induce enantiomeric excess in asymmetric syntheses was tested.
