NAD(P)+-NAD(P)H model. 52. Reduction of olefins by Hantzsch ester on silica gel.
Nakamura, Kaoru; Fujii, Masayuki; Ohno, Atsuyoshi; Oka, Shinzaburo.
Tetrahedron Lett. (1984), 25(36), 3983-6.
Abstract
Olefinic double bonds in a,b-unsatd. carbonyl or nitro compds. are reduced chemoselectively by Hantzsch ester (I) on silica gel in excellent yields.
In this letter, we wish to report that silica gel is such a good catalyst as to promote the reduction of carbon-carbon double bonds in simple a,B-un-saturated ketones and aldehydes or in a,b-unsaturated nitro compounds.
In a typical run, a mixture of 1 mmole of a substrate, 1.5 mmoles of 3,5-di-carboethoxy-2,6-dimethyl-1,4_dihydropyridine (Hantzsch ester, HEH), and 1 g of silica gel (5) in 15 mL of benzene was kept at 80°C for 17 hr under an argon atmosphere in the dark. Then, the solvent was evaporated from the reaction mixture and the residue was subjected either to a column chromatography on silica gel with an eluent of benzene-hexane mixture or to a preparative GLPC (PEG 20 m, 70 - 160°C), yielding the corresponding product. Results are summarized in the Table.
5) Silica gel was purchased from Nakarai Chem. Co. Ltd., (silica gel 60, 35-70 mesh).
beta-nitrostyrene yield% 100 (84)
b) Determined on GLPC.
c) Numbers in parentheses are isolated yields after
column chromatography or preparative GLPC.
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