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Transition-metal-controlled synthesis of (.+-.)-aristeromycin and (.+-.)-2',3'-diepi-aristeromycin. An unusual directive effect in hydroxylations by Barry M. Trost; Gee Hong. Kuo; Torre. Benneche is a Chemistry article available to read on EtoBox.

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The biological significance of carbocyclic analogues of nucleosides and of hydroxyalkylated purines' and the widespread use of protecting groups in the synthesis of such compounds led us to explore whether transition-metal-catalyzed alkylations would enhance selectivity and, consequently, improve synthetic efficiency. An initial question relates to regioselectivity as exemplified by the reaction of 2-pyrimidinone with vinyl epoxide 1 (eq 1). Unlike the case of carbon nucleophiles,\* a lower propensity for attack distal to oxygen to give the 1,Cproduct exists3 The ratio of 2:3 increases by switching from THF to 2:l THF/HMPA and also by using triisopropyl phosphite rather than triphenylphosphine as ligand. The choice of vinyl epoxide can also play a role as shown by the contrast between the acyclic and cyclic epoxides 4 and 5 in which exclusive 1,2-attack can be achieved in the former case to give 64 and 1,Cattack in the latter case to give 7.4 The success of the latter experiment led us to explore a synthesis of the carbanucleoside natural product ari~teromycin~,~ in which the regio-and diastereoselectivity of the 1 ,Csubstitution would be totally controlled by Pd(0) templates. Duri

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Author

Barry M. Trost; Gee Hong. Kuo; Torre. Benneche

Published

1988

Language

EN

Field

Chemistry (Physical Sciences)