(–)-Nomilin chloroform solvate

Abstract

The absolute stereochemistry of the title compound, C28H33O9·CHCl3, has been determined by single‐crystal X‐ray diffraction by incorporation of the heavy‐atom‐containing solvent chloro­form. The A/B, B/C and C/D ring junctions are all trans‐fused. Five‐membered ring E is equatorially attached to ring D. The crystal structure is stabilized by weak inter­molecular C—H⋯O inter­actions.

Deacetylnomilin monohydrate

“…The C-bound H atoms were positioned geometrically and were included in the refinement in the riding-model approximation, with C-H = 0.93 Å (alkenyl H), 0.96 Å (CH 3 ), 0.97 Å (CH 2 ), 0.98 Å (CH) and O-H = 0.82 Å and with U iso (H) = 1.2U eq (C) (alkenyl, methylene and methine) and = 1.5U eq [C(methyl) and O]. The absolute structure determined for (-)-nomilin (Zhang et al, 2006) was invoked: the Flack parameter determined for the parent compound not being definitive [-0.19 The molecular structure of the title compound showing 50% probability displacement ellipsoids and the atom-numbering scheme.…”

“…For general background to the title compound, see: Dreyer (1965); Munehiro et al (1989). For the absolute configuration of (À)-nomilin, see: Zhang et al (2006). For details of ring conformations and puckering parameters, see: Cremer & Pople (1975); Boeyens (1978).…”

“…2). The absolute configuration determined for the parent (-)-nomilin (Zhang et al, 2006) was invoked, giving the assignments C1(S), C5(R), C8(R), C9(R), C10(S), C12(S), C13(S), C16(R), C17(R) for the 9 chiral centres in the molecule (using the numbering scheme employed in Fig. 1).…”

Triterpenoids

“…189 Crystal structures have been reported for obacunone 190 and nomilin. 191 Two new obacunone derivatives 313 and 314 have been isolated from Citrus sudachi. 192 Turrapubesin A 315 is a halogenated limonoid from Turraea pubescens where it occurs with turrapubesin B 316 B which contains a rare maleimide moiety.…”