Synthesis of Pyrano‐ and Pyrido‐Anellated Pyranosides as Precursors for Nucleoside Analogues
作者:Gabriela Thiele、Holger Feist、Klaus Peseke
DOI:10.1081/car-200053709
日期:2005.4.1
The push-pull activated methyl (3Z)-4,6-O-benzylidene-3-[(methylthio)methylene]-3deoxy-alpha-D-erythro-hexopyranosid-2-ulose (1) reacted with dialkyl malonate in the presence of potassium carbonate to give the alkyl (2R,4aR,6S,10bS)-4a,6,8,10b-tetrahydro-6-methoxy-8-oxo-2-phenyl-4H-pyrano[3',2':4,5]pyrano[3,2-d] [1,3]dioxine-9-carboxylates 2 and 3. Treatment of 1 with 3-oxo-N-phenyl-butyramide, N-(4-methoxy-phenyl)-3-oxobutyramide, and 3-oxo-N-o-tolyl-butyramide, respectively, in the presence of potassium carbonate and 18-crown-6 yielded the (2R,4aR,6S,10bS)-9-acetyl-7-aryl-4,4a,7,10b-tetrahydro-6-methoxy-2-phenyl[1,3]dioxino-[4',5':5,6]pyrano[3,4-b]pyridin-8 (6H)-ones 4-6. (2R,4aR,6S,10bS)-4,4a,8,10b-Tetrahydro-6-methoxy-8-oxo-2-phenyl-4H-pyrano [3',2':4,5]pyrano[3,2-d][1,3]dioxine-9-carboxamide (7) was prepared by anellation reactions of I either with malononitrile or with cyanoacetamide.