Sigma complexes of transition metals in organic synthesis. III. Regioselective condensation of phenoxyallyltitanium reagents with carbonyl compounds

The organotitanium σ complex produced by the reaction of lithium derivatives of allyl phenyl ether with (i-PrO)3TiCl reacts with aldehydes and ketones, forming α-regioisomeric condensation products with high selectivity. In the case of the organotitanium derivatives of γ-substituted allyl phenyl ethers the γ-regioisomeric products are formed. The effect of the nature of the carbonyl compound and the allyl phenyl ether on the stereoselectivity of condensation is studied