Chemical R&D, Pfizer Global R&D, MS-8118D/4002, Eastern Point Road, Groton, Connecticut 06340, USA.
J Org Chem. 2010 Feb 5;75(3):945-7. doi: 10.1021/jo902159z.
2,2,2-Trifluoro- and trichloroethyl imidates, which are easily prepared by reaction of a nitrile and a trihaloethanol in the presence of HCl, have proven to be excellent reagents for the preparation of amidines under mild reaction conditions. Depending on the nature of the amine nucleophile, the imidates can react either as the free-base or the hydrochloride salt in a telescoped process. In several cases, the p-bromobenzoate salt of the desired product was directly isolated from the reaction mixture.
2,2,2-三氟代和三氯乙基异氰酸酯很容易通过腈与三卤代乙醇在 HCl 存在下反应制备,已被证明是在温和反应条件下制备脒的优良试剂。根据胺亲核试剂的性质,异氰酸酯可以在缩合过程中作为游离碱或盐酸盐反应。在几种情况下,所需产物的对溴苯甲酸盐可直接从反应混合物中分离得到。