Ethyl (4-benzyloxyphenyl)-6-methyl-2-sulfanylidene-1,2,3,4-tetrahydropyrimidine-5-carboxylate and a redetermination of ethyl (4RS)-4-(4-methoxyphenyl)-6-methyl-2-sulfanylidene-1,2,3,4-tetrahydropyrimidine-5-carboxylate, as its 0.105-hydrate, both at 200 K: subtly different hydrogen-bonded ribbons

Balladka K Sarojini; Hemmige S Yathirajan; Eric C Hosten; Richard Betz; Christopher Glidewell

doi:10.1107/S2053229614026758

Ethyl (4-benzyloxyphenyl)-6-methyl-2-sulfanylidene-1,2,3,4-tetrahydropyrimidine-5-carboxylate and a redetermination of ethyl (4RS)-4-(4-methoxyphenyl)-6-methyl-2-sulfanylidene-1,2,3,4-tetrahydropyrimidine-5-carboxylate, as its 0.105-hydrate, both at 200 K: subtly different hydrogen-bonded ribbons

Acta Crystallogr C Struct Chem. 2015 Jan;71(Pt 1):59-64. doi: 10.1107/S2053229614026758. Epub 2015 Jan 1.

Authors

Balladka K Sarojini¹, Hemmige S Yathirajan², Eric C Hosten³, Richard Betz³, Christopher Glidewell⁴

Affiliations

¹ Industrial Chemsitry Section, Department of Chemistry, Mangalore University, Mangalagangotri 574 199, India.
² Department of Studies in Chemistry, University of Mysore, Manasagangotri, Mysore 570 006, India.
³ Department of Chemistry, Nelson Mandela Metropolitan University, Summerstrand Campus (South), University Way, Summerstrand, PO Box 77000, Port Elizabeth, 6031, South Africa.
⁴ School of Chemistry, University of St Andrews, Fife KY16 9ST, Scotland.

PMID: 25567577
DOI: 10.1107/S2053229614026758

Abstract

Two sulfanylidene-1,2,3,4-tetrahydropyrimidine derivatives have been synthesized using acid-catalysed cyclocondensation reactions between thiourea, ethyl 3-oxobutanoate and substituted benzaldehydes. In each of ethyl (4RS)-4-(4-benzyloxyphenyl)-6-methyl-2-sulfanylidene-1,2,3,4-tetrahydropyrimidine-5-carboxylate, C21H22N2O3S, (I), where Z' = 2, and ethyl (4RS)-4-(4-methoxyphenyl)-6-methyl-2-sulfanylidene-1,2,3,4-tetrahydropyrimidine-5-carboxylate 0.105-hydrate, C15H18N2O3S·0.105H2O, (II), the reduced pyrimidine ring adopts a conformation intermediate between the boat, screw-boat and twist-boat forms. In (I) and (II), a combination of N-H...O and N-H...S hydrogen bonds links the organic molecules into ribbons containing alternating R2(2)(8) and R4(4)(20) rings. In (I), the ribbon contains three types of ring, viz. two different R2(2)(8) rings which are both centrosymmetric and R4(4)(20) rings which are not centrosymmetric. In (II), the ribbon contains two types of ring, both of which are centrosymmetric. In compound (II), the ribbons enclose continuous channels which run along the twofold rotation axes in the space group C2/c, and the partial-occupancy water molecules lie within these channels. Structural comparisons are made with a number of related compounds.

Keywords: N—H...O and N—H...S hydrogen bonding; crystal structure; cyclocondensation reaction; multicomponent reactions; racemic 1,2,3,4-tetrahydropyrimidine-5-carboxylate esters.