GABA antagonists synthesis

A number of phosphonate and phosphinate derivatives where the phosphorus atom is directly bonded to non-aromatic cyclic systems have been reported. The synthesis and reactions of a number of compounds with the general structure 103 have been reported. Enantiomerically pure cyclopropanephosphonic acids which are constrained analogues of the GABA antagonist phaclophen, have been prepared by stereocontrolled Michael addition of a-anions derived from chiral chloromethylphosphonamides 104 to a,P-unsaturated esters followed by in situ cyclisation. Other asymmetric syntheses include those of (/ )- and (S)-piper-idin-2-ylphosphonic acid (105) via the addition to trialkyl phosphites to iminium salt equivalents and 4-thiazolidinylphosphonate 106 by catalytic asymmetric hydrophosphonylation of 3-thiazoline. In the latter case both titanium and lanthanoid (which give much better e.e. values) chiral catalysts are used. 

Hanessian, S., Cantin, L.-D., Roy, S., Andreotti, D., and Gomtsyan, A., The synthesis of enantiomerically pure, symmetrically substituted cyclopropane phosphonic acids. A constrained analog of the GABA antagonist phaclophen, Tetrahedron Lett., 38, 1103, 1997. 

Wermuth, C. G., Bourguignon, J.-J., Schlewer, G Gies, J.-P., Schoenfelder, A., Melikian, A., et al. (1987) Synthesis and structure-activity relationships of a series of aminopyridazine derivatives of y-aminobutyric acid acting as selective GABA-A antagonists../. Med. Chem. 30, 239-249. 

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