CHIRAL TRIPOD LIGANDS - A NEW SYNTHETIC R OUTE TO CHIRAL C(1)-SYMMETRICAL NEOPENTYLTRIS(PHOSPHANE) LIGANDS H3CC[CH2P(R(A))2][CH2P(R(B))2][CH2P(R(C))2]

A novel synthesis of chiral tripod ligands H3CC[CH2P-(R(a))2][CH2P(R(b ))2][CH2P(R(c))2] (6) containing three different donor groups at their neopentyl backbone is described. The key intermediates H3CC[CH2P(R(a) )2][CH2P(R(b))2](CH2OH) (3) are easily obtained starting from pentagly cerine, H3CC-(CH2OH)3, via the oxetanes CH2OCH2C(CH3)CH2[P(R(a))2] (2) following published procedures. The compounds 3, after protection of the phosphane functions by BH3 {formation of H3CC[CH2P(R(a))2BH3][CH2P (R(b))2BH3](CH2OH) (4)} are transformed into the mesylates H3CC[CH2P(R (a))2BH3][CH2P(R(b))2BH3](CH2OMs) (5), which upon reaction with KP(R(c ))2 and deprotection with morpholine gives fair yields of racemic 6. T he synthetic route described is thus a valuable and efficient alternat ive to a recently published procedure, based on H3CC(CH2Cl)(CH2Br)(CH2 OSO2CF3) as the key intermediate. The compounds 2-6 are obtained in an alytically pure form and are fully characterised by spectroscopic data .