The structure of PO-substituted norcaradienes. I. The crystal and molecular structure of 7-dimethoxyphosphoryl-7-phenylnorcaradiene

Abstract

7-Dimethoxyphosphoryl-7-phenylnorcaradiene crystallizes in the space group P1, with a= 13.259 (2), b = 8"698 (3), c = 6.507 (2) A, e = 110.97 (2), ,8= 97.62 (2), y= 91 "26 (3) . The structure has been soh, ed by direct methods; refinement by block-diagonal least-squares cycles gave R=4.07% for 2184 observed reflexions collected on a Siemens single-crystal diffractometer with Cu K~ radiation. Whereas in solution a rapid equilibrium between the norcaradiene and its valence-isomeric cycloheptatriene can be observed, the molecules in the crystalline state show clearly the norcaradiene structure with an endo phenyl ring.The three C-C bonds of the cyclopropane ring are equal within the standard deviation.

Conformational analysis of cycloheptane, oxacycloheptane, 1,2‐dioxacycloheptane, 1,3‐dioxacycloheptane, and 1,4‐dioxacycloheptane

“…This trend is consistent with the 1,3‐dioxa isomer being the most stable structure in the series 1,2‐dioxacyclohexane (1,2‐dioxane), 1,3‐dioxacyclohexane (1,3‐dioxane), and 1,4‐dioxacyclohexane (1,4‐dioxane) as well as in the series 3,6‐dihydro‐1,2‐dioxin, 4 H ‐1,3‐dioxin (1,3‐diox‐4‐ene), and 2,3‐dihydro‐1,4‐dioxin (1,4‐dioxene) 68. The relative energies are influenced by lone pair repulsion, bond angles, torsion angles, and stereoelectronic (anomeric) effects 58–61, 68.…”

“…It is difficult to study the more flexible seven‐membered rings because there are minima and transition states with similar energies and geometries and with low energy barriers among the twist chair, chair, boat, and twist boat conformations and transition states. In addition, many cycloheptane derivatives are polycrystalline or highly disordered solids at room temperatures 53–58.…”

The structure of PO-substituted norcaradienes. II. The crystal and molecular structures of dimethyl 2,5-dichloro-7-phenylnorcaradiene-7-phosphonate and dimethyl 2,5-dibromo-7-phenylnorcaradiene-7-phosphonate

“…II (1) Dreissig, Luger, Rewicki & Tuchscherer (1973). (2) Maas, Fischer & Regitz (1974). (3) This work.…”

“…In a previous paper, we have reported the structure of (Ia) (Maas, Fischer & Regitz, 1974). In this molecule, stabilization of the norcaradiene skeleton can only be explained by electronic and steric interaction of the C(7) substituents with the molecular orbitals of the cyclopropane ring and perhaps with the diene system.…”

Chemistry of Phosphorylcarbenes

“…The (a-diazo-0-hydroxyaIkyl)diphenylphosphane oxides Normally therefore phosphoryldiazoalkanes are converted photolytically into phosphorylcarbenes, photolysis being car-(21 )- (29) are obtained on C-alkylation of (diazomethy1)di-ried out under a Philips mercury high-pressure 125 W HPK lamp with a Duran 50 filter. Table 2.…”