Triclinic modification of N-[(1,1-di-methyl-ethoxy)carbon-yl]-3-[(R)-prop-2-en-1-ylsulfin-yl]-(R)-alanine ethyl ester at 120†(1) K.

There are two independent mol-ecules in the asymmetric unit of the title compound, C(13)H(23)NO(5)S. In the crystal structure, inter-molecular N-H⋯O hydrogen bonds link mol-ecules into two independent one-dimensional chains along [100]. The crystal studied was found to be a non-merohedral twin with a ratio of 0.615†(6):0.385†(1) for the refined components. At 200†(1)†K [Singh et al. (2009 ▶). Acta Cryst. E65, o1385-o1386] the crystal structure of the title compound contains one disordered mol-ecule in the asymmetric unit of a monoclinic unit cell.