Methyl N-{(1R)-2-[(methoxycarbonyl)oxy]-1-phenylethyl}carbamate

The chiral title compound forms supramolecular chains, through N—H⋯O hydrogen bonds between the amide and carboxylate groups.


Structure description
Methyl carbamate, Me(O)CONH 2 , the methyl ester of carbamic acid, is an important intermediate in the manufacture of carbamate-based resins used in the textile and polymer industries.On a smaller scale, it is also a pharmaceutical intermediate.The primary amine group can be functionalized, in the same way as for primary amides.From another point of view, the formation of a carbamate via a N-methyloxycarbonylation reaction can also be considered as a useful protection of a primary amine (Sartori et al., 2004).Finally, alternative routes allow both the formation of the carbamate and the Nfunctionalization.The title compound, C 12 H 15 NO 5 , resulted from such a reaction, between methyl chloroformate and a chiral amino alcohol, namely (R)-2-phenylglycinol, under basic conditions, and using Ca(OH) 2 as a heterogeneous catalyst.
We assumed that the R absolute configuration of the starting material was retained during the reaction, affording an enantiomerically pure compound, which crystallized in the Sohncke space group P2 1 2 1 2 1 .Molecular dimensions are as expected, and the amide group displays a geometry quite different from that of the carboxylate group, with bond lengths C2-N1 = 1.333 (3) and C10-O3 = 1.445 (3) A ˚(Fig. 1).The geometry of the carbamate group is virtually identical to that observed in the closely related chiral compound methyl(1S-phenylethyl) carbamate, which crystallizes with four independent molecules in the asymmetric unit (Thakar et al., 2018).
In the extended structure, the amide NH group serves as a donor, forming an intermolecular hydrogen bond with the carboxylate group C11 O4 of a neighbouring molecule (Table 1).Infinite chains are then formed in the crystal, running along the short a axis (Fig. 2).Molecules are further connected through weak C-H� � �O contacts involving the methyl group of the carbamate moiety as donor.Chains are arranged in the crystal with two neighbouring chains having the phenyl rings facing upwards (Fig. 3).However, no significant �-� contacts are observed: the distance separating two rings is large [4.6763 (17) A ˚] and the dihedral angle between corresponding mean planes is 21.84 (13) � .Aside from the weak C-H� � �O bonds mentioned above and van der Waals contacts, no other significant interactions between the supramolecular chains are present in the crystal structure.As a consequence, the Kitaigorodskii packing index of 67.8% is rather low for this small organic molecule (Spek, 2020).

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2.The amide H atom (H1) was refined with free coordinates and isotropic displacement parameter.Other H atoms are in calculated positions.The absolute configuration was inferred from the synthesis.(Sheldrick, 2015b), XP in SHELXTL-Plus (Sheldrick, 2008), Mercury (Macrae et al., 2020) and publCIF (Westrip, 2010).

Figure 3
Figure 3Part of the crystal structure of the title compound, viewed down the crystallographic a axis.The asymmetric unit is shown as a ball and stick model, and the dashed line represents the weak �-� interaction between phenyl rings.

Table 2
Experimental details.