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US 5,703,248 AGranted
Process for the selective trihalogenation of ketones useful as intermediates in the synthesis of thiophenes
OwnerJeffrey S. Rommel, James T. Traxler +1inventors
InventorsJeffrey S. Rommel, James T. Traxler, Richard R. Boettcher
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Abstract
The present invention concerns a novel process for the selective trihalogenation of ketones employing organic halogen salts.
Claims12
A process for the selective trihalogenation of a compound of formula II:
- ##STR12## wherein R.sub.10 represents hydrogen and R.sub.11 represents hydroxy or R.sub.10 and R.sub.11 represent an extra bond, to yield a compound of formula I ##STR13## wherein X represents halogen, which comprises halogenating at a temperature range of about 20.degree. to 100.degree. C., the compound of formula II with molecular halogen in the presence of an organic halogen salt of the formula III ##STR14## wherein X is halogen and each of R.sub.1, R.sub.2, R.sub.3, and R.sub.4 is independently hydrogen or optionally substituted alkyl, phenyl, or benzyl wherein at least one of R.sub.1, R.sub.2, R.sub.3, and R.sub.4 is other than hydrogen, in the range of 2 to 20 moles % which produces halide ions soluble in an organic solvent.
A process for the preparation of a compound of formula I:
- ##STR15## wherein X represents halogen which comprises halogenating at about 20.degree. to 100.degree. C. a compound of formula II:
- ##STR16## wherein R.sub.10 represents hydrogen and R.sub.11 represents hydroxy or R.sub.10 and R.sub.11 represent an extra bond, with molecular halogen in the presence of a compound of formula III:
- ##STR17## wherein X is halogen and each of R.sub.1, R.sub.2, R.sub.3, and R.sub.4 is independently hydrogen or optionally substituted alkyl, phenyl, or benzyl wherein at least one of R.sub.1, R.sub.2, R.sub.3, and R.sub.4 is other than hydrogen which produces halide ions soluble in an organic solvent.
A process for preparing a compound of formula IVa or IVb ##STR18## which comprises cyclising in the presence of sulfide ions a compound of formula I ##STR19## wherein each X is halogen.
A process for preparing N-(2,4-dimethylthien-3-yl)-N-(1-methoxyprop-2-yl)-chloracetamide comprising the steps of
- a) cyclising in the presence of sulfide ions a compound of formula I ##STR20## wherein each X is halogen to produce a compound of formula IVa or IVb;
- b) reacting a compound of formula IVa or IVb with 1-methoxy-2-propylamine to produce N-(1-methoxyprop-2-yl)-2,4-dimethylamino thiophene;
- and
- c) N-chloracetylating N-(1-methoxyprop-2-yl)-2,4-dimethylamino thiophene with chloracetylchloride.
1 more element
Dependencies are inferred from the claim text.