Unusually large reactivity differences in the transformation of cyclopropane lactones to 1‐aminocyclopropane‐1‐phosphonic acids and their carboxylic acid analogues

Synthesis methods of (1-aminocyclopropyl)phosphonic acids

“…The reaction is accelerated by the addition of a catalytic amount of 4-dimethylaminopyridine (DМАР) [35]. For example, in the absence of DMAP the yield of the latter reaction decreased to 48%.…”

“…It is possible to remove the Boc-protection selectively, utilizing 1 N HCl in ether [34] or boron trifl uoride etherate in dichloromethane; therewith the O-protective tertbutyldimethylsilyl group is also removed [35].…”

“…The amides are commonly obtained by the opening of the lactone ring with ammonia (or methylamine) in alcohol solution [34,35] (Scheme 9).…”