01903nas a2200193   4500008004100000022001400041245016200055210006900217260000800286520116300294653001501457653001201472653001601484653001401500653001301514100002401527700002801551856013001579       2019                        eng d  a2193-580700aHemiketal-keto tautomerism in 2-deoxy-delta-lactones mediated by 2-lithiothiazole in solution state: a formal synthesis of DAH, Kamusol and their C-5 Epimers0 aHemiketalketo tautomerism in 2deoxydeltalactones mediated by 2li  cOCT3 a<p>The reactions of 2-lithiothiazole on 3,4,6-tri-O-benzyl-2-deoxyglyconolactones have been studied, which resulted in the formation of two products, major (3,4,6-tri-O-benzyl-2-deoxy-1-(2-thiazolyl) glycal) and minor products 3,4,6-tri-O-benzyl-2-deoxy-1-(2-thiazolyl) glycal hemiketal. The hemiketal-keto tautomerism in solution was observed in the minor product. The tautomerism has been studied in various organic solvents and their ratios have been determined by H-1 NMR spectroscopy. The major product from the reaction of 2-lithiothiazole with 2-deoxygluconolactone was utilized for the synthesis of 3-deoxy-D-arabino-2-heptulosonic acid DAH 4 a and 3-deoxy-D-arabino-2-heptulopyranose commonly known natural product kamusol 6 a via acid catalyzed hydration followed by stereoselective methyl glycoside bond formation. Similarly, major product from 2-deoxygalactonolactone furnished 5-epi-DAH 4 b (C-5 epimer of 4 a) and 5-epi-kamusol 6 b (C-5 epimer of 6 a). The minor product has also been utilized for the synthesis of DAH 4 a, 5-epi-DAH 4 b, kamusol 6 a and 5-epi-kamusol 6 b through a common intermediate, alpha-methyl glycosylated product.</p>
10ahemiketals10aKetones10atautomerism10athiazoles10aumpolung1 aChand, Hemender, R.1 aBhattacharya, Asish, K.  uhttps://library.ncl.res.in/content/hemiketal-keto-tautomerism-2-deoxy-delta-lactones-mediated-2-lithiothiazole-solution-state