(3S)-3-Benzyloxymethyl-1,4-dioxane-2,5-dione

Abstract

Key indicatorsSingle-crystal X-ray study T = 150 K Mean (C-C) = 0.006 Å R factor = 0.043 wR factor = 0.102 Data-to-parameter ratio = 7.1 For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e. # 2005 International Union of Crystallography Printed in Great Britain -all rights reservedThe lactide ring in the title compound, C 12 H 12 O 5 , adopts a screw-boat conformation. C-HÁ Á ÁO interactions link the molecules into a chain in the [100] direction. CommentThe structure of the title compound, (I), was determined in the course of our investigations towards a better understanding of the regioselectivity observed in the ring-opening polymerization of various substituted (3S)-3-benzyloxymethyl-1,4-dioxane-2,5-dione derivatives (Leemhuis et al., 2005). Earlier, we reported the crystal structures of the 6(R)-methyl (Kooijman et al., 2005a) and the 6(S)-methyl derivatives (Kooijman et al., 2005b). The molecular structure of (I) is displayed in Fig. 1 and selected geometric parameters are given in Table 1. The lactide ring has taken a somewhat deformed screw-boat conformation. The asymmetry parameter (Duax & Norton, 1975) ÁC 2 (C2-O3) = 6.4 (5) ; all other asymmetry parameters have values of 18 or higher. The Cremer & Pople puckering parameters (Cremer & Pople, 1975) Figure 1 Atomic displacement plot (Spek, 2003) of the title compound, showing the atom-numbering scheme. The displacement ellipsoids are drawn at the 50% probability level.

Functionalized Poly(α-hydroxy acid)s via Ring-Opening Polymerization: Toward Hydrophilic Polyesters with Pendant Hydroxyl Groups

“…X-ray crystal structure analyses of monomers 4a (S,S diastereoisomer) and 4b revealed that both substituents on 4a are at the equatorial position of the dilactone ring which has a twisted boat configuration (Figure 3, top). 46 The substituents are in such a position that there is hardly any difference in steric hindrance for attacking either of the carbonyl groups. Compound 4a is therefore attacked in a random way yielding a random polymer.…”

“…The crystal structure at the bottom of Figure 3 shows that compound 4b clearly has two different steric bulks on each side of the dilactone ring. 47 A benzyloxymethyl substituent is on one side and two hydrogens are on the other. This steric difference results in a regioselective ring opening during polymerization.…”

“…O -Bn- l -serine ( 1 ) maintains its chirality throughout the entire reaction sequence depicted in Scheme , and monomer 4b was obtained as optically pure and crystalline material. However, with the addition of racemic 2-bromopropionyl bromide, a second stereo center is introduced which leads after the intramolecular ring closing reaction to the dilactones as a mixture of two diastereoisomers: the S , S and the S , R forms. , These diastereoisomers were separated by flash column chromatography and subsequent crystallization. In this study, only the ( S , S ) isomer was used for polymerization.…”

“…Compound 4a is therefore attacked in a random way yielding a random polymer. The crystal structure at the bottom of Figure shows that compound 4b clearly has two different steric bulks on each side of the dilactone ring . A benzyloxymethyl substituent is on one side and two hydrogens are on the other.…”

Synthesis and characterization of 3-methyl-6-[(propynyloxy)methyl]-1,4-dioxane-2,5-dione

“…A search in the Cambridge Structural Database (Version 5.38 with two updates; Groom et al, 2016) for pure and functionalized lactides (i.e. glycolides with one methyl substituent) returned 25 entries, including different lactide stereoisomers (Kooijman et al, 2014;Fedushkin et al, 2009;van Hummel et al, 1982) and other derivatives (Zhang et al, 2015;Fiore et al, 2010;Kooijman et al, 2005;Bolte et al,1994;Lynch et al, 1990).…”