01126nas a2200157   4500008004100000022001400041245014200055210006900197260010600266300001200372490000700384520040300391100002600794700002000820856012800840       2007                        eng d  a0040-402000aGeneral and efficient route to 3 `-deoxy-3 `-N-, S-, and C-substituted altropyranosyl thymines from 2',3'-O-anhydro-mannopyranosylthymine0 aGeneral and efficient route to 3 deoxy3 N S and Csubstituted alt  aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLANDbPERGAMON-ELSEVIER SCIENCE LTDcJAN  a602-6080 v633 a<p>An efficient route to 1-(2,3-O-anhydro-4,6-O-phenylmethylene–D-mannopyranosyl) thymine from 1,2,4,6-tetra-O-acetyl-3-O-tosyl-beta-D-glucopyranose has been devised. This newly synthesized epoxide is opened up regioselectively at the C-3'-position by N-, S-, and C-nucleophiles to afford a wide range of new 3-deoxy-3'-substituted altropyranosyl thymines. (c) 2006 Published by Elsevier Ltd.</p>1 aDeshpande, Sachin, G.1 aPathak, Tanmaya  uhttps://library.ncl.res.in/content/general-and-efficient-route-3-deoxy-3-n-s-and-c-substituted-altropyranosyl-thymines-23-o01931nas 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-001705nas a2200229   4500008004100000022001400041245010000055210006900155260009900224300001400323490000800337520079800345653001101143653003001154653002101184653002801205653003901233100002601272700003001298700002001328856012701348       2008                        eng d  a0008-621500aStudies on the synthesis and unusual behavior of vinyl sulfone-modified hexenopyranosylthymines0 aStudies on the synthesis and unusual behavior of vinyl sulfonemo  aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLANDbELSEVIER SCI LTDcMAY  a1163-11700 v3433 a<p>Although vinyl sulfone-modified- (VSM) pent-2-enofuranosyl nucleosides 2 and hex-2-enopyranosyl glycoside 4 are easily synthesized from the corresponding mesylated sulfones le and 3c, respectively, via an oxidation-mesylation-elimination route, the 3'-C-sulfonyl-hex-2'-enopyranosylthymine 11 is not obtained from 10 and a glycal derivative 12 is formed instead. On the other hand, 3-C-sulfonyl-hex-3'-enopyranosylthymine 20 is easily synthesized from the mesylated sulfone 19. Again unlike the reaction patterns of VSM-pent-T-enofuranosyl nucleosides 2 and hex-2-enopyranosyl glycosides 4 as Michael acceptors, the reactions of nucleophiles with 3'-C-sulfonyl-hex-3'-enopyranosylthymine 20 yielded a rearranged product 21 instead of Michael adducts. (c) 2008 Published by Elsevier Ltd.</p>10aglycal10ahexopyranosyl nucleosides10aMichael addition10aunsaturated nucleosides10avinyl sulfone-modified nucleosides1 aDeshpande, Sachin, G.1 aSuresh, Cheravakkattu, G.1 aPathak, Tanmaya  uhttps://library.ncl.res.in/content/studies-synthesis-and-unusual-behavior-vinyl-sulfone-modified-hexenopyranosylthymines-001657nas a2200241   4500008004100000022001400041245019300055210006900248260009900317300001400416490000800430520060900438653001701047653002101064653004101085653004001126653004101166100001801207700003001225700002101255700002001276856011901296       2008                        eng d  a0008-621500aUnusual addition of amines to C-2 of vinyl sulfone-modified-beta-D-pent-2-enofuranosyl carbohydrates: synthesis of a new class of beta-anomeric 2-amino-2,3-dideoxy-D-threo-pentofuranosides0 aUnusual addition of amines to C2 of vinyl sulfonemodifiedbetaDpe  aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLANDbELSEVIER SCI LTDcJUN  a1287-12960 v3433 a<p>When 3-C-sulfonyl-pent-2-enofuranosides and 3-C-sulfonyl-hex-2-enofuranosides were reacted with primary and secondary amines, only the beta-anomeric methoxy group of the pent-2-enofuranoside did not cause any hindrance to incoming nitrogen nucleophiles. This resulted in the `unusual' addition of amines, in which the diastereoselectivity of the reaction was overwhelmingly in favor of amino sugars of the D-arabino configuration. Selected products were desulfonylated to obtain a new class of beta-anomeric 2-amino-2,3-dideoxy-D-threo-pentofuranosides. (C) 2008 Elsevier Ltd. All rights reserved.</p>10aamino sugars10adeoxyaminosugars10adesulfonylation with Mg-MeOH-NiBr(2)10adiastereoselective Michael addition10avinyl sulfone-modified carbohydrates1 aDas, Indrajit1 aSuresh, Cheravakkattu, G.1 aDecout, Jean-Luc1 aPathak, Tanmaya  uhttps://library.ncl.res.in/content/unusual-addition-amines-c-2-vinyl-sulfone-modified-beta-d-pent-2-enofuranosyl-001853nas a2200205   4500008004100000022001400041245017600055210006900231260007100300300001200371490000700383520098900390100002401379700002601403700001901429700002301448700002901471700002001500856012701520       2010                        eng d  a0022-326300aExperimental and theoretical study on the remarkable influence of protecting groups on the selectivity of addition of amines to vinyl sulfone-modified hex-2-enopyranosides0 aExperimental and theoretical study on the remarkable influence o  a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcJAN  a303-3140 v753 a<p>Although phenylmethylene-protected vinyl sulfone-modified carbohydrate 2 alpha reacts with both primary and secondary amines in Michael fashion to afford aminated products, only primary amines react with the dibenzyl-protected 3 alpha, 6-O-trityl-protected 4 alpha, and unprotected 5 alpha, highlighting for the first time the remarkable influence of protecting, groups on the reaction patterns of vinyl sulfone-modified carbohydrates. The quantum chemical calculations suggest that the Michael addition of amines and proton transfer to vinyl sulfone-modified carbohydrates 2 alpha and 5 alpha are possible via relay process in a concerted mechanism. These calculations reveal that the addition of primary amines to vinyl sulfone-modified carbohydrate is preferential due to the low activation energy barriers, whereas the addition of secondary amines has relatively higher activation energy barriers. The theoretical conclusions are in line with the experimental observations.</p>1 aBhattacharya, Rahul1 aKesharwani, Manoj, K.1 aManna, Chinmoy1 aGanguly, Bishwajit1 aSuresh, Cheravakattu, G.1 aPathak, Tanmaya  uhttps://library.ncl.res.in/content/experimental-and-theoretical-study-remarkable-influence-protecting-groups-selectivity-0