CRYSTAL-STRUCTURES OF BACLOFEN ANALOGS - 3-THIENYLAMINOBUTYRIC AND 3-FURYLAMINOBUTYRIC ACIDS

X-ray crystal structures of 4-amino-3-(2-thienyl) butyric acid (compou nd 1), 4-amino-3-(4-bromo-2-thienyl) butyric acid (compound 2), and 4- amino-3-(5-methyl-2-furyl) butyric acid (compound 3) are reported. Spa ce groups and unit/cell parameters are: compound 1, monoclinic, P2(1)/ c, a = 13.288(3), b = 5.23 1 (1), c = 12.388(2) angstrom, beta = 92.3( 1)-degrees; compound 2, monoclinic, P2(1)/c, a = 12.610(7), b = 5.156( 1), c = 15.814(8) angstrom, beta = 101.8(1)-degrees; compound 3, ortho rhombic, Pccn, a = 11.461(1), b = 25.284(2), c = 6.977(1) angstrom. Fi nal R indices are: compound 1, 0.057; compound 2, 0.069; compound 3, 0 .060. Conformations of their gamma-aminobutyric chains are compared wi th the one of gamma-amino-beta-(p-chlorophenyl)-butyric acid (baclofen , compound 4). Two different types of conformations are observed, i.e. , conformations (i) with folding (compound 3) or (ii) without folding (compounds 1, 2, and 4) of the ammonium group toward the heteroaromati c or aromatic ring. However, distances between ionized groups are cons tant.