METAL TEMPLATE SYNTHESIS OF A 14-MEMBERED TRANS-P2S2 CHELATING MACROCYCLE

The R*,R* and R*,S* forms of teh 14-membered trans-P2S2 chelating macrocycle 5,6,7,9,14,15,16,18-octahydro-5,14-dimethyldibenzo[e,l][1,8,4,11]dithiadiphosphacyclotetradecin have been isolated in low yields from the dimerization of deprotonated (+/-)-(2-mercaptoethyl)(2-methoxybenzyl)methylphosphine on platinum(II) in the presence of boron tribromide. The crystal structure of the monoacetone solvate of the nickel(II) perchlorate derivative of the R*,R* diastereomer of the macrocycle has been determined. Crystal data for C23H32Cl2NiO9P2S2: monoclinic, P2(1)/n, a = 8.988 (1) angstrom, b = 23.660 (3) angstrom, c = 14.257 (2) angstrom, beta = 94.15 (1)-degrees, Z = 4, and R = 0.040. The complex is formed stereoselectively with the relative helicities of the four chiral donor stereocenters being R*P, R*P, S*S, and S*S because of exo coordination of the nickel(II) ion to the macrocyclic ring. The byproducts of the metal-template synthesis are seven-membered (+/-)-2-methyl-2-phospha-5-thiabicyclo[5.4.0]undeca-1(7),8,10-triene and its boron tribromide adduct; the latter is the principal product of the reaction, and its crystal structure has been determined. Crystal data for C10H13BBr3PS: moncolinic, P2(1)/c, a = 14.200 (2) angstrom, b = 17.074 (3) angstrom, c = 13.429 (2) angstrom, beta = 113.14 (1)-degrees, Z = 8, and R = 0.038.