5-Bromo-5-bromomethyl-2-phenoxy-1,3,2-dioxaphosphorinan-2-one

In the title 1,3,2-dioxaphosphorinane derivative, C10H11Br2O4P, the 1,3,2-dioxaphosphorinane ring adopts a chair conformation, having the P=O bond equatorially oriented and the phenoxy group axially oriented. The bromo substituent is in an axial position opposite to the phenoxy group and the bromomethyl group is in an equatorial position opposite to the P=O bond. In the crystal packing, molecules are linked through weak C—H⋯O and C—H⋯Br interactions to form chains along the b axis. The chains are arranged into sheets parallel to the ab plane. In adjacent sheets, molecules are arranged in an antiparallel fashion. Intermolecular C—H⋯π interactions are also observed.

In the title 1,3,2-dioxaphosphorinane derivative, C 10 H 11 Br 2 O 4 P, the 1,3,2-dioxaphosphorinane ring adopts a chair conformation, having the P O bond equatorially oriented and the phenoxy group axially oriented. The bromo substituent is in an axial position opposite to the phenoxy group and the bromomethyl group is in an equatorial position opposite to the P O bond. In the crystal packing, molecules are linked through weak C-HÁ Á ÁO and C-HÁ Á ÁBr interactions to form chains along the b axis. The chains are arranged into sheets parallel to the ab plane. In adjacent sheets, molecules are arranged in an antiparallel fashion. Intermolecular C-HÁ Á Á interactions are also observed.
Reaction of phosphate triesters with N-bromosuccinimide (NBS) results in the formation of a dibromo derivative ( Fig. 1).
In the crystal packing shown in Fig. 2, the molecules are linked through weak C-H···O interactions (Table 1) to form chains along the b axis which generate S(6) ring motifs (Bernstein et al., 1995). The chains are arranged into sheets parallel to the ab plane. In the adjacent sheets, the molecules are arranged in an anti-parallel fashion (Fig. 3). The adjacent sheets are connected through weak C-H···O interactions (Table 1) and Br···Br short contacts with the Br···Br distance of 3.8771 (9) Å (symmetry code: 1 -x, 1/2 + y, 1/2 -z). The crystal is stabilized by weak C-H···O, C-H···Br interactions and C-H···π interactions (Table 1); Cg1 is the centroid of the C5-C10 ring.
Upon prolonged heating for a period of 8 h, no improvement has been observed with respect to yield nor new spot was observed as monitored by thin layer chromatography. The CCl 4 layer was then stripped off and the gummy material was dissolved in dichloromethane (100 ml) and washed well with water (2 × 100 ml) and then with brine. The organic layer was dried (Na 2 SO 4 ) and concentrated to afford the crude product as a light brown gum which was passed through a silica gel (100-200 mesh) column eluting with dichloromethane to get the pure title compound as a white crystalline solid (0.32 g, 60%; m.p. 361-362 K).
supplementary materials sup-2 Refinement All H atoms were constrained in a riding motion approximation, with C aryl -H = 0.93 Å and 0.97 Å for CH 2 . The U iso (H) values were constrained to be 1.2U eq of the carrier atom. The highest residual electron density peak is located at 0.72 Å from Br1 and the deepest hole is located at 0.61 Å from Br2. Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids and the atomic numbering.    Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.