A Versatile Protocol for theSynthesis of Oxazole and 3-Nitro/3-Carbethoxy PyrroleC-Nucleosides using TOSMIC

Abstract

The synthesis of oxazole and pyrrole C-nucleosides using TOSMIC in moderate to good yields is reported.

‘In situ’ Generated ‘HCl’ - An Efficient Catalyst for Solvent-Free Hantzsch Reaction at Room Temperature: Synthesis of New Dihydropyridine Glycoconjugates

“…The combined organic layers were dried (Na 2 SO 4 ) and evaporated under vacuum to give the product. {6-[2,2-Dimethyl-(4S)-1,3-dioxolan-4-yl]-2,2-dimethyl-(3aR,6R,6aS)-tetrahydrofuro[3,4-d][1,3]dioxol-4-yl}-2,6dimethyl-1,4-dihydropyridine-3 FABMS: m/z (%) = 539 (M + , 9), 287 (8), 252 (18). Dimethyl-4-[2,2,7,7-tetramethyl-(3aR,5S,5aS,8aS,8bR)…”

“…The protocols reported for the synthesis of Cglycosylated DHPs by Dondoni et al 6a (4Å MS, DMF, reflux, 48 h, low yields) and Tewari et al 6b (Bu 4 NHSO 4 , diethylene glycol, reflux, 2 h), warranted to look for better reaction conditions to prepare such compounds. In view of our continued studies on the synthesis of new saccharides 7 and C-nucleosides 8 by new synthetic methods, 9 herein, we report our results on 'HCl', generated in situ from 2,4,6-trichloro[1,3,5]triazine (TCT, cyanuric chloride) 10 -catalyzed efficient protocol for the synthesis of 1,4-dihydropyridines and their glycoconjugates (Scheme 1) at room temperature under solvent-free reaction conditions with enhanced reaction rates and high yields.…”

p-Toluenesulfonylmethyl Isocyanide (TosMIC)

“…11 (H) Recently, the synthesis of C-nucleosides by the TosMIC approach from sugar-derived aldehydes and other Michael acceptors was reported. 12…”

Stereoselective synthesis of new dihydropyrimidinone glycoconjugates #

“…Hence, better reaction conditions were warranted to prepare such libraries of compounds. In view of our continued studies on the synthesis of new saccharides [12] and C-nucleosides [13], herein, we report, the HCl, generated in situ from 2,4,6-trichloro[1,3,5]-triazine (TCT) [14], catalyzed efficient protocol for cyclocondensation of sugar derived aldehydes with enhanced reaction rates under solvent free Biginelli conditions at room temperature, to result the glycoconjugates in high yields (Scheme 1).To establish the reaction conditions, 1-O-methyl 2,3-Oisopropylidene-α-D-mano-pentoaldo-1,4-furanose (1, Table 1) was subjected to reaction with equimolar quantities of ethyl acetoacetate and urea at room temperature in the presence of TCT (10 mol%) to furnish DHPM glycoconjugates 1a and 1b (Table 1), as a separable mixture of diastereoisomers in 76% and 11% yields respectively. The structures of 1a and 1b were unambiguously assigned from the spectral analysis.…”