Lipase-catalyzed kinetic resolution of cis-1-diethylphosphonomethyl-2-hydroxymethylcyclohexane. Application to enantioselective synthesis of 1-diethylphosphonomethyl-2-(5′-hydantoinyl)cyclohexane

The Bucherer-Bergs Multicomponent Synthesis of Hydantoins-Excellence in Simplicity

Hydantoins and their hybrids with other molecules represent a very important group of heterocycles because they exhibit diverse biological and pharmacological activities in medicinal and agrochemical applications. They also serve as key precursors in the chemical or enzymatic synthesis of significant nonnatural α-amino acids and their conjugates with medical potential. This review provides a comprehensive treatment of the synthesis of hydantoins via the Bucherer-Bergs reaction including the Hoyer modification but limited to free carbonyl compounds or carbonyl compounds protected as acetals (ketals) and cyanohydrins used as starting reaction components. In this respect, the Bucherer-Bergs reaction provides an efficient and simple method in the synthesis of important natural products as well as for the preparation of new organic compounds applicable as potential therapeutics. The scope and limitations, as well as a comparison with some other methods for preparing hydantoins, are also discussed.

Development of Biologically Active Compounds on the Basis of Phosphonic and Phosphinic Acid Functionalities

Phosphonic and phosphinic acids, especially α-heteroatom-substituted ones, possess unique structural and physical features which enable them to act as hydrotically stable analogs to biological phosphates in biological processes. They also act as mimetics in the transition state of the protease-induced hydrolysis of dipeptides. The first half of this review focuses on selected new synthetic methods developed by our research group for the stereoselective synthesis of α-heteroatom-substituted phosphonic and phosphinic acid derivatives, including modified nucleotide analogs and phosphinyl dipeptide isosteres. In the latter half, this review summarizes the utility of difluoromethylenephosphonic acids and phosphonic acid esters in the development of enzyme inhibitors against protein tyrosine phosphatases, sphingomyelinases, purine nucleoside phosphorylases and thrombin. The enzyme inhibitors developed were used as probes to elucidate signal transductions and the mechanisms of enzyme actions. The findings of the studies are briefly described.

[Synthesis of phosphonic acid and phosphinic acid derivatives for development of biologically active compounds]

This paper covers recent publications from our laboratory on the synthesis of a variety of phosphonate and phosphinate derivatives. New methods for the enantioselective synthesis of alpha-hydroxyphosphonates were established by Lewis acid-mediated cleavage of homochiral 1,3-dioxaneacetals with P(OEt)(3) and chiral metal ligand-mediated hydrophosphonylation of aldehydes. Two diastereomers of HPmp derivatives were prepared by an application of these methods. The HPmp derivatives were convered to FPmp derivatives but with low diastereoselectivity. Hydrophosphonylation of alpha-aminoaldehydes afforded threo- and erythro-beta-amino-alpha-hydroxyphosphonates under chelation and nonchelation controlled conditions, respectively. The asymmetric dihydroxylation of alpha, beta-, and beta, gamma-unsaturated phosphonates with AD-mix-alpha and AD-mix-beta reagents gave alpha, beta- and beta, gamma-dihydroxyphosphonates with high enantioselectivity. The method was applied to the kinetic resolution of racemic alpha-oxygetated beta, gamma-unsaturated phosphonates. Treatment of allyloxymethylphosphonates with the base afforded alpha-hydroxyphosphonates via the [2,3]-Wittig reaction. Threo- and erythro-beta-amino-alpha-hydroxyphosphinates were obtained with high diastereoselectivity by phosphinylation of alpha-aminoaldehydes in the presence of (R)- and (S)-ALB, respectively. The phosphinylation of alpha-oxygenated aldehydes afforded the corresponding alpha, beta-dioxygenated phosphinates, but with low diastereoselectivity. Sphingomyelin analogues containing CF(2)PO(OH)(2) were synthesized starting from (S)- and (R)-Garner aldehyde for the purpose of obtaining potent sphyngomyelinase inhibitors. A useful method for the synthesis of alpha, alpha-difluorobenzylphosphonates was established based on the cross coupling reaction of an iodobenzene derivative with ZnCuBr(2)CF(2)PO(OEt)(2). The synthetic utility of ZnCuBr(2)CF(2)PO(OEt)(2) was examined to obtain alpha, alpha-difluoromethylenenphosphonates. The method was applied to a synthesis of PNP-inhibitory active compounds by combination of the purine base and alcohols containing difluoromethylenephosphonate. The methodology for the beta-selective N-glycosylation of 2,3-dideoxy glucoside was established by introducing phosphonothioates at the 3-position of glycosyl doners instead of phosphonate. Synthesis of new acylic nucleotide analogues designed based on the structural modification of ARS2267 is also described. Finally, kiral synthesis of some phosphonates was achieved using lipase through kinetic resolution.

5-Carboxamido-1,3,2-dioxaphosphorinanes, potent inhibitors of MTP

5-Carboxamido-1,3,2-dioxaphosphorinanes have been identified as potent inhibitors of microsomal triglyceride-transfer protein. The 1,3,2-dioxaphosphorine functionality acted as a neutral and stable replacement for piperidine and piperidine N-oxide.