α-Amino-C-phosphinic acids and derivatives are an important group of compounds of synthetic and medicinal interest and particular attention has been dedicated to their stereoselective synthesis in recent years. Among these, phosphinic pseudopeptides have acquired pharmacological importance in influencing physiologic and pathologic processes, primarily acting as inhibitors for proteolytic enzymes where molecular stereochemistry has proven to be critical. This review summarizes the latest developments in the asymmetric synthesis of acyclic and phosphacyclic α-amino-C-phosphinic acids and derivatives, following in the first case an order according to the strategy used, whereas for cyclic compounds the nitrogen embedding in the heterocyclic core is considered. In addition selected examples of pharmacological implications of title compounds are also disclosed.
Phenylphosphonic acid is an efficient, friendly and reusable heterogeneous catalyst for the synthesis of α-aminophosphonates through a ‘one-pot’ three-component reaction of amines, carbonyl compounds and dialkyl phosphites under solvent-free conditions. This methodology illustrates a very simple procedure, with wide applicability, extending the scope to aliphatic and aromatic amines, aliphatic and aromatic aldehydes and aliphatic ketones. It also enabled the synthesis of α-aminophosphonates in large scale, clean conversion, easy workup and purification. Excellent results were obtained in each case obtaining the desire compounds in moderate to good yields.
We report here a practical and efficient synthesis of α-aminophosphonic acid incorporated into 1,2,3,4-tetrahydroquinoline and 1,2,3,4-tetrahydroisoquinoline heterocycles, which could be considered to be conformationally constrained analogues of pipecolic acid. The principal contribution of this synthesis is the introduction of the phosphonate group in the N-acyliminium ion intermediates, obtained from activation of the quinoline and isoquinoline heterocycles or from the appropriate δ-lactam with benzyl chloroformate. Finally, the hydrolysis of phosphonate moiety with simultaneous cleavage of the carbamate afforded the target compounds.
We report here an alternative and practical method for the preparation of 1,2,3,4-tetrahydroisoquinoline-1-phosphonic acid and the first synthesis of 1,2,3,4-tetrahydroisoquinoline-1-H-phosphinic and 1,2,3,4-tetrahydroisoquinoline-1-phenylphosphinic acids through Kabachnik–Fields and aza-Pudovik reaction. This methodology does not require any metallic catalyst and proceeds under mild reaction conditions.
17 November 2015 in European Journal of Organic Chemistry