Cyclopropanation process
AssigneeGivaudan SA
InventorFridtjof Schroder
Life of this patent
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Abstract
A method for the preparation of cyclopropyl carbinols by cyclopropanation of unsaturated alcoholates, utilizing a reagent system selected from (A) magnesium metal and dibromomethane, and (B) dibromomethane and a tertiary Grignard reagent, the reaction being carried out in the presence of an ether solvent. The process is useful, for example, for the preparation of ingredients for the flavor and fragrance industry.
Claims6
A method for the preparation of a compound of the formula
- comprising the generation of an alcoholate of the formula II
- and the subsequent cyclopropanation of this alcoholate with a reagent system selected from (A) magnesium metal and dibromomethane, and (B) dibromomethane and a tertiary Grignard reagent, the reaction being carried out in the presence of an ether solvent, Cα, Cβ, Cγ and Q being selected according to the possibilities (a) or and (b):
- (a) Cα, Cβ, Cγ represent carbon atoms that may be protonated or substituted with up to a total of 5 substituents for all three carbon atoms, the substituents being selected from the group consisting of alkyl, alkenyl, cycloalkyl and cycloalkenyl groups;
- and Q represents a moiety selected from
- (i) a saturated or unsaturated carbon chain having from 1-6 carbon atoms, which carbon atoms are protonated or substituted, the substituents being selected from any of those of Cα, Cβ, Cγ;
- and
- (ii) a single covalent bond joining Cα and Cβ;
- and;
- (b) Cα, Cβ, Cγ and all or part of Q together form a cycloalkyl or cycloalkenyl ring;
- and
- (c) M is an alkali metal, an alkaline earth metal, or an alkaline earth metal monohalide.
A method of preparation of a cyclopropyl carbinol, comprising the generation of an allylic alcoholate and the cyclopropanation of this allylic alcoholate with a reagent system selected from (A) magnesium metal and dibromomethane and (B) dibromomethane and a tertiary Grignard reagent, the reaction being carried out in the presence of an ether solvent.
A method for the preparation of (1-methyl-2-(1,2,2-trimethylbicyclo[3.1.0]-hex-3-ylmethyl)cyclopropyl)methanol comprising the step of:
- reacting 2-ethyl-4(2,2,3-trimethyl cyclopentyl-3-enyl)but-2-en-1-ol with a lithium reagent and then magnesium and dibromomethane in the presence of an ether solvent.
Dependencies are inferred from the claim text.