Radical-mediated stannylation of vinyl sulfones: access to novel 4′-modified neplanocin A analogues

Synthesis of 4'-substituted (halogeno, phenyl, ethynyl, and cyano) neplanocin A analogues was carried out. A cyclopentenol derivative having a vinylstannane structure was designed as key-intermediate in this study, which was prepared based on radical-mediated sulfur-extrusive stannylation. The resulting stannylated cyclopentenol 15 was successfully condensed with 6-chloropurine through the Mitsunobu reaction, leading to the carbocyclic nucleoside 20. Compound 20 was converted to its adenine counterpart 21 by treatment with NH(3)/MeOH, during which the 4'-stannyl group remained intact. The title compounds were prepared by using 21 or the 4'-iodo derivative (22) mostly through the Stille reaction. (C) 2009 Elsevier Ltd. All rights reserved.