[1122-70-9] · C8H9N · 2-Methyl-6-vinylpyridine · (MW 119.18)
Physical Data: clear liquid, bp 65-70 °C/12 mmHg.
Solubility: sol all common organic solvents.
Preparative Method: prepared in a two-step procedure from 2,6-Lutidine in an overall 30% yield.5
Handling, Storage, and Precautions: store under nitrogen at rt; unpleasant odor; use in a fume hood.
2-Methyl-6-vinylpyridine is a stable, masked equivalent of two moles of Methyl Vinyl Ketone that has been utilized in the synthesis of steroid ring systems.2,3 In addition, 2-methyl-6-vinylpyridine derivatives have found use as a convenient synthon of 1,5-diketones.4 Alkylation of the vinylpyridine2,3,6 followed by Birch reduction of the appropriately protected substrate generates a cyclohexenone (eq 1).
The mode of cyclization of the intermediate 1,5-diketone is predictable and dependent on the substitution pattern (eq 2). Thus Birch reduction of 2-cyclohexylethyl-6-methylpyridine (1) (R = cyclohexyl) produces 100% of 3-cyclohexylethylcyclohex-2-enone (2) (R = cyclohexyl), while reduction of the corresponding 2-ethyl-6-methylpyridine (1) (R = H) affords >90% 2,3-dimethylcyclohex-2-enone (3) (R = H).4c
Other examples of heterocyclic bis-annulation reagents include 3-chloromethyl-2,4-dimethylisoxazole,7 N-benzyl-2,6-dicyanopiperidine,8 and 2,6-dimethyl-4H-pyran-4-one.9
Methyl Vinyl Ketone.
Arthur A. Nagel
Pfizer Central Research, Groton, CT, USA