H. Takayanagi et Y. Morinaka, HIGHLY STEREOSELECTIVE SYNTHESIS OF TRISUBSTITUTED GAMMA,DELTA-UNSATURATED ACID AND ALDEHYDE VIA KETAL CLAISEN REARRANGEMENT, Chemistry Letters, (7), 1995, pp. 565-566
A new sequence for the highly stereoselective (E>99%) synthesis of a t
risubstituted gamma,delta-unsaturated acid (3), which consists of a ke
tal Claisen rearrangement of a terpene allylic alcohol with 2,2-dimeth
oxy-3-methyl-3-butanol and a subsequent oxidative cleavage of the resu
lting alpha-ketol, is applicable even to the preparation of 3 which is
difficult to synthesize by traditional methods. The related procedure
for preparation of the corresponding aldehyde is also described.