Uncovering stereochemical relations in a compound with a stereogenic N-O axis: methyl 2-(4-methyl-2-thioxo-2,3-dihydrothiazol-3-yloxy)propanoate.
The geometry of racemic methyl 2-(4-methyl-2-thioxo-2,3-dihydrothiazol-3-yloxy)propanoate, C(8)H(11)NO(3)S(2), (I), is characterized by a distorted heterocyclic five-membered ring and an enantiomorphic N-alkoxy substituent, which is inclined at an angle of -68.8 degrees to the thiazolethione plane in (M)-(I). The unit cell consists of a 1:1 ratio of R,P- and S,M-configured molecules of (I). The combination of a P configuration at the N-O axis and an R configuration at the asymmetric propanoate C(beta) atom on one side, and an S,M configuration on the other side, is considered to originate from steric interactions. The largest substituent at the asymmetric propanoate C(beta) atom, i.e. the methoxycarbonyl group, resides above the methyl substituent; the medium-sized propanoate gamma-methyl substituent points in the opposite direction with respect to the N-O bond, whereas the H atom is located above the C=S double bond of the thiazolethione subunit.
Hartung
Jens
J
Fachbereich Chemie, Organische Chemie, Technische Universität Kaiserslautern, Erwin-Schrödinger-Strasse, D-67663 Kaiserslautern, Germany. hartung@chemie.uni-kl.de
Schwarz
Michaela
M
Svoboda
Ingrid
I
Fuess
Hartmut
H