01931nas a2200193   4500008004100000022001400041245012800055210006900183260010600252300001600358490000700374520110400381100002201485700002401507700002401531700003001555700002001585856013201605       2008                        eng d  a0040-402000aDiastereoselective addition of planar N-heterocycles to vinyl sulfone-modified carbohydrates: a new route to isonucleosides0 aDiastereoselective addition of planar Nheterocycles to vinyl sul  aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLANDbPERGAMON-ELSEVIER SCIENCE LTDcNOV  a10406-104160 v643 a<p>Michael-type addition reactions of planar N-heterocycles at the C-2 positions of vinyl sulfone-modified carbohydrates provide an efficient and general route for the carbon-N-heterocycle bond formation. Therefore, the addition pattern of planar heterocycles, such as imidazole, triazole, thymine, and adenine to 3-C-phenyisulfonyl-hex-2-enopyranosides (1 alpha/1 beta) and 3-C-p-toluenesulfonyl-pent-2-enofuranosides (2 alpha/2 beta) was studied for developing a general methodology for the synthesis of new classes of isonucleosides possessing a carbon-N-heterocycle linkage at C-2 positions of furanosyl and pyranosyl sugars. To a great extent, the anomeric configurations of the starting vinyl sulfones play crucial roles in deciding the diastereoselectivity of addition of heterocycles. However, the trityl protected 3-C-p-toluenesulfonyl-hex-2-enopyranosides (33 alpha/33 beta) were judged to be More practical starting materials for desulfortylation and deprotection for the synthesis of a new class of thymine and adenine deoxyisonucleosides. (C) 2008 Elsevier Ltd. All rights reserved.</p>1 aSanki, Aditya, K.1 aBhattacharya, Rahul1 aAtta, Ananta, Kumar1 aSuresh, Cheravakkattu, G.1 aPathak, Tanmaya  uhttps://library.ncl.res.in/content/diastereoselective-addition-planar-n-heterocycles-vinyl-sulfone-modified-carbohydrates-new-0