2,3-O-Isopropylidene-2,3-dihydroxy-l ,4-bis

When the reaction of CCXXI and diethyl sodiomalonate is carried out with an added chiral ligand such as ( + )-2,3-0-isopropylidene-2,3-dihydroxy-l, 4-bis(diphenylphosphino)butane, (+)-o-anisylcyclohexylmethylphosphine, (—)-dimethylisopropylphosphine, or (—)-spartein, the coupling product (CCXXII) is formed in up to 24% optical yield (Trost and Dietsche, 1973). 

The paper describes the first asym. hydroboration with a chiral catalyst. E A soln. of norbornene and catalytic amounts of chloro(l,5-cyclooctadiene)rhodium(I) dimer and DIOP (2,3-0-isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)butane) in THF flushed with argon, stirred at 20° for 15 min, cooled to —78°, 1.2 eqs. catecholborane added, stirred for 5 min, allowed to warm to —40°, maintained at this temp, for 72 h, recooled to —78°, ethanol, 3 M NaOH, and 30% H2O2 added, the mixture allowed to warm to 25° during ca. 1 h, then stirred for 12h cjco-(lR, 2R)-norborneol. Y 99% (e.e. 55%). The method is generally applicable (even to 1,1-disubst. ethylene derivs. ) and expensive chiral boron-reagents are not necessary. F.e.s. K. Burgess, M.J. Ohlmeyer, J. Org. Chem. 53, 5178-9 (1988) from allyl alcohol O-derivs. s. Tetrahedron Letters 30, 395-8 (1989). 

---