767. The crystal structure of 2 : 3-dihydro-2 : 3-methylene-1 : 4-naphthaquinone

Abstract

The compound (I) crystallises in a form that is convenient for structure analysis by X-ray difiraction. The crystals belong to the monoclinic system, with a = 6-98, b = 10.55, c = 5.46 A, and p = 944O, and there are two molecules in the unit cell, with the space group P2Jm. The molecule is bisected by a crystallographic plane of symmetry. The benzenoid ring, which lies perpendicular to this plane, is itself coplanar; but the quasiquinonoid residue is non-coplanar, and the two carbonyl bonds are not collinear. Bond lengths and bond angles have been determined with moderate accuracy, including those in the three-membered ring; and the stereochemistry has been studied in some detail at the heavily strained carbon atoms by which this ring is fused to the naphthaquinone system.

The crystal and molecular structures of two derivatives of a spiro-oxazolone: a cis vs trans X-ray study

“…So it seems there is no significant difference between the two molecules, within the experimental error; moreover, there seems to exist good agreement between some individual bond distances, the C-C bonds being the more susceptible to variations. The bonds of the cyclopropane rings show a shortening from the normal C(sp3)-C(sp 3) bond because of the triangular bending, which is also reflected in the geometry outside the cyclopropane ring, as is recorded in the literature (Riche & Pascard-Billy, 1975;Lemley, Skarstad & Hughes, 1976;Grant & Speakman, 1958;Carlstr6m, 1975;Schenk, 1971;Beintema, 1976). The differences within the ring have to be referred to the difference in degree of substitution at each corner (Meester, Schenk & MacGillavry, 1971), the effect of which may also be noticed in the areas of the triangles, 0.986 and 0.991 A2, which are between the theoretical values of 0.977 A 2 for cyclopropane and 0.996 A 2 for cyclopropylidene (Lathan, Radon, Hariharan, Hehre & Pople, 1973).…”

Reaction of 2-methyl-1,4-naphthoquinone and its 3-substituted derivatives with active methylene group anions and with diazo compounds

“…This contains two exchangeable protons, one of which being enolic and relatively acidic would be expected l 3 to resonate at very low field, as is observed. The two exchangeable protons attached to nitrogen in structure(21) would be expected to have chemical shifts similar to one another. Structure (21), moreover, should show three carbonyl stretching bands in the i.r.…”