The crystal structure of (4S)-5-(2-methoxy-2-oxoethylamino)-5-oxo-4-(3,4,5- trimethoxybenzamido) pentanoic acid 5 (C18H24N2O9, Mr = 412.39) has been determined by single- crystal X-ray diffraction analysis. The crysta...The crystal structure of (4S)-5-(2-methoxy-2-oxoethylamino)-5-oxo-4-(3,4,5- trimethoxybenzamido) pentanoic acid 5 (C18H24N2O9, Mr = 412.39) has been determined by single- crystal X-ray diffraction analysis. The crystal belongs to monoclinic, space group P21/c with a = 27.665(9), b = 5.1444(16), c = 13.907(4) ?, β = 98.401(5)o, V = 1958.0(11) ?3, Z = 4, Dc = 1.399 g/cm3, μ = 0.113 mm-1, F(000) = 872, R = 0.0606 and wR = 0.1405 (I > 2σ(I)). The results con- firmed that 5 could be assigned to the tautomeric form. The intermolecular hydrogen bonds between O(5)–H(5)…O(7), N(2)–H(2)…O(6) and N(1)–H(1)…O(4) have been observed.展开更多
All four isomers of a novel fl-branched unusual amino acid were designed and synthesized with high stereoselectivity （〉 90% de） and in 33%--44% overall yields by the use of 4（R/S）-5,5-dimethyl-4-phenyl-oxazolidin...All four isomers of a novel fl-branched unusual amino acid were designed and synthesized with high stereoselectivity （〉 90% de） and in 33%--44% overall yields by the use of 4（R/S）-5,5-dimethyl-4-phenyl-oxazolidin-2-one as the chiral auxiliary via asymmetric 1,4-Michael addition, direct or indirect azidation, hydrolysis and hydrogenation reactions.展开更多
基金The project was supported by the National Natural Science Foundation of China (No. 20272033) and the Doctoral Foundation of Ministry of Education of China (No. 20020422024)
文摘The crystal structure of (4S)-5-(2-methoxy-2-oxoethylamino)-5-oxo-4-(3,4,5- trimethoxybenzamido) pentanoic acid 5 (C18H24N2O9, Mr = 412.39) has been determined by single- crystal X-ray diffraction analysis. The crystal belongs to monoclinic, space group P21/c with a = 27.665(9), b = 5.1444(16), c = 13.907(4) ?, β = 98.401(5)o, V = 1958.0(11) ?3, Z = 4, Dc = 1.399 g/cm3, μ = 0.113 mm-1, F(000) = 872, R = 0.0606 and wR = 0.1405 (I > 2σ(I)). The results con- firmed that 5 could be assigned to the tautomeric form. The intermolecular hydrogen bonds between O(5)–H(5)…O(7), N(2)–H(2)…O(6) and N(1)–H(1)…O(4) have been observed.
基金Project supported by the National Natural Science Foundation of China （Nos. 20472071, 20562014 and 30860342） and Natural Science Foundation of Yunnan Province （No. 2009cc017）.
文摘All four isomers of a novel fl-branched unusual amino acid were designed and synthesized with high stereoselectivity （〉 90% de） and in 33%--44% overall yields by the use of 4（R/S）-5,5-dimethyl-4-phenyl-oxazolidin-2-one as the chiral auxiliary via asymmetric 1,4-Michael addition, direct or indirect azidation, hydrolysis and hydrogenation reactions.
