Substituted diones as intermediates for a process for the manufa

Details Substituted diones as intermediates for a process for the manufa Substituted diones as intermediates for a process for the manufa

1991-07-12

1992-10-13

Chan, Nicky

Organic compounds -- part of the class 532-570 series

Organic compounds

Carboxylic acid esters

560262, 560112, 560110, 560 74, 560 66, 560 55, 560 20, C07C 6500, C07C 6521, C07C 69025

Patent

active

051552540

ABSTRACT:
A process for the manufacture of 3-hydroxy-2-alkyl-4-pyrones of formula I is provided. ##STR1## The process comprises cyclizing a compound of formula II, ##STR2## an acidic medium and hydrolyzing the ester formed thereby to produce compound I. R.sup.1 represents methyl or ethyl; R.sup.2 represents lower alkanoyl or optionally substituted benzoyl; R.sup.3 represents --OH or --NR.sup.4 R.sup.5 ; and, R.sup.4 and R.sup.5 may be alike or different and represent lower alkyl. The pyrones of formula I wherein R.sup.1 represents methyl or ethyl are known flavorants and odorants.

REFERENCES:
patent: 3832357 (1974-08-01), Higuchi et al.
Cavaliere, Chem. Rev., 1947, pp. 525-584.
M. Koreeda and H. Akagi, Tetrahedron Letters 21, (1980) 1197-1200.
H. O. House, "Modern Synthetic Reactions", 2nd Edition, W. A. Benjamin, Menlo Park, CA, 1972, pp. 629-631, 734, 747-754.
R. F. Abdulla and R. S. Brinkmeyer, Tetrahedron 35, (1979) 1675, 1697-1726, 1732-1735.

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