79809-14-6Relevant articles and documents
SYNTHETIC APPLICATION OF LITHIATION REACTIONS - XVI: SYNTHESES OF (+/-)TETRAHYDROPALMATINE, (+/-)CANADINE, (+/-)STYLOPINE AND (+/-)SINACTINE
Narasimhan, N. S.,Mali, R. S.,Kulkarni, B. K.
, p. 1975 - 1982 (1983)
N,N-Dimethyl-3,4-dimethoxy- and methylenedioxybenzylamines were lithiated and the organolithium intermediates treated with paraformaldehyde to give the 2-hydroxymethyl derivatives.The latter were converted to 7,8-dimethoxy- and methylenedioxyisochroman-3-ones through successive reaction with ClCOOEt, KCN and KOH.The isochromanones on condensation with homoveratrylamine or homopiperonylamine, followed by cyclisation and reduction furnished the protoberberine alkaloids.
Total synthesis of (-)-tetrahydropalmatine via chiral formamidine carbanions: Unexpected behavior with certain ortho-substituted electrophiles
Matulenko, Mark A.,Meyers
, p. 573 - 580 (2007/10/03)
A method has been developed by alkylation of chiral lithioformamidines to construct protoberberine alkaloids with a C(9) and C(10) D-ring substitution pattern. This ring pattern was established using an ortho-substituted hydroxymethylbenzene electrophile protected as a silyl ether to ultimately provide (-)-tetrahydropalmatine in 88% ee. Additionally, we have discovered limitations with ortho-substituted electrophiles in the asymmetric formamidine alkylation. These electrophiles have the potential to disrupt the lithium formamidine chelate and cause the selectivity in the alkylation to be uncharacteristically low. The total synthesis of (±)-canadine and (-)-tetrahydropalmatine along with the limitations to the formamidine alkylation technology are delineated herein.