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US 4,308,378 AGranted
Cis/trans isomerization of 6-(substituted-aryl-ethenyl)-3,4,5,6-tetrahydro-4-hydroxy-2H-pyran-2-one s
AssigneeMerck & Co., Inc.
InventorGerald E. Stokker
Life of this patent
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Abstract
Biologically inactive cis-6-(substituted-arylethenyl)-3,4,5,6-tetrahydro-4-hydroxy-2H-pyran-2-on es are isomerized to the corresponding anti-hypercholesterolemic trans-isomers by heating in the presence of a heavy metal salt.
Claims6
A process for the preparation of the transisomer of the compound with structural formula:
- ##STR8## wherein R.sub.1, R.sub.2 and R.sub.3 are each selected from
- (a) hydrogen,
- (b) halogen,
- (c) C.sub.1-4 alkyl,
- (d) C.sub.1-4 haloalkyl,
- (e) phenyl,
- (f) phenyl substituted by
- (1) halogen,
- (2) C.sub.1-4 alkoxy,
- (3) C.sub.2-8 alkanoyloxy,
- (4) C.sub.1-4 alkyl, or
- (5) C.sub.1-4 haloalkyl, and
- (g) OR.sub.4 in which R.sub.4 is
- (1) hydrogen,
- (2) C.sub.2-8 alkanoyl,
- (3) benzoyl,
- (4) phenyl,
- (5) halophenyl
- (6) phenyl C.sub.1-3 alkyl,
- (7) C.sub.1-9 alkyl,
- (8) cinnamyl,
- (9) C.sub.1-4 haloalkyl,
- (10) allyl,
- (11) cycloalkyl-C.sub.1-3 alkyl,
- (12) adamantyl-C.sub.1-3 alkyl, or
- (13 ) substituted phenyl-C.sub.1-3 alkyl in each of which the substituents are selected from
- (i) halogen,
- (ii) C.sub.1-4 alkoxy,
- (iii) C.sub.1-4 alkyl, or
- (iv) C.sub.1-4 haloalkyl;
- which comprises heating in an aqueous inert organic solvent in the presence of a heavy metal salt derived from a cation of a metal selected from mercury, zinc, lead, and cadmium and an anion selected from bromide, chloride, fluoride, iodide, nitrate and sulfate, the corresponding cis-isomer of structure:
- ##STR9##
29 more elements
Dependencies are inferred from the claim text.