Process for preparing 2-methylpyrrolidine and specific enantiomers thereof
The invention relates to a process for preparing 2-methylpyrrolidine and, more particularly, specific enantiomers of 2-methylpyrrolidine. Novel intermediates also are described.
1. A process for preparing a compound of formula (V):
wherein R 1 is hydrogen or a nitrogen-protecting group, or a salt thereof, comprising the steps of:
4a) providing a compound of formula (III):
wherein * denotes a chiral center that can be designated as a R— or S-stereocenter, R p is a nitrogen-protecting group, and R 2 is an unsubstituted alkyl, substituted alkyl, unsubstituted aryl, or substituted aryl group, and treating the compound of formula (III) with an alkali metal iodide salt to obtain a compound of the formula (IV):
wherein * and R p are as defined for a compound of formula (III); and
4b) hydrogenating a compound of formula (IV) to obtain a desired enantiomer of a compound of formula (V):
wherein * and R 1 are as previously defined.
2. The process according to claim 1 , wherein step 4a) is substituted with a step comprising reacting a compound of formula (II):
wherein * is as previously defined and R p is a nitrogen-protecting group, with an iodine reagent to obtain a compound of formula (IV).