5a -c) C6H5 ( 2 a -c ) ((1): R = R, f h j : R = R, (0: R = R A tion at the phosphorus atom, and in the case of (2c) for incorporation of the k C triple bond by thermal elimination of trimethylchloro~ilane~~]. Procedure Chlorophenyl(trimethylsily1)methane (72.4 g, 360 mmol) is converted with Mg (10.0 g, 400 mmol) in diethyl ether (200 ml) into the Grignard compound, which is then added dropwise slowly to an ice-cooled solution of PC13 (49 g, 360 mmol) in ether (150 ml). MgClz is removed by filtration and the filtrate is evaporated down under vacuum. Fractional distillation of the residue furnishes 52.7 g (55%) of (lc), b.p.A solution of (lc) (15.0 g, 57 mmol) in ether (200 ml) is treated with 25.3 g (220 mmol) of 1,4-diazabicycl0[2.2.2]0~tane and the mixture is stirred for 12 h at room temperature.The insoluble material is filtered off and washed with ether. The combined filtrates are then evaporated down under vacuum and the amine hydrochloride which precipitates is removed by filtration. After removal of solvent the residue is treated with n-pentane, filtered and the filtrate evaporated down and distilled yield 7.1 g (54%) of (2c), b.p. 51 "C/10-) torr.53"C/10-3 torr ["P('H)-NMR (C6D6): 6=189].

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Stereospecific syntheses of (f )-ferruginol and (f)-hinokione were achieved in which the tricyclic ring system was assembled in the order C -BC -ABC. The key features of the approach involve: (1) the utilization of a lactone bridge as part of an enone protecting group in ring A; (2) the installation of an isopropyl group by the regioselective addition of lithium dimethylcuprate to a cross-conjugated dienone; (3) the elimination of the lactone bridge with concomitant aromatization of ring C; and (4) the reductive methylation of the enone in ring A to install the C-4 geminal dimethyl group and to guarantee the trans fusion of the AB rings.

Die 3,4‐Stereochemie von Aldoladdukten läßt sich mit dem neuen, chiralen, gut zugänglichen Enolat‐Reagens (2) erstmals kontrollieren; d. h. aus dem chiralen Aldehyd (1) kann sowohl das 3,4‐anti‐ als auch das 3,4‐syn‐Aldoladdukt (3) bzw. (4) als überwiegendes Produkt gewonnen werden: (2a) bildet (3a) und (4a) im Verhältnis 15:1, mit (2b) entstehen (3b) und (4b) im Verhältnis 1:10.