[reaction: see text]. Upon treatment with n-BuLi at low temperatures, a variety of allyl 1,1-dichlorovinyl ethers 2 undergo rearrangement to furnish gamma,delta-unsaturated esters 3 after alcohol addition. Compounds containing quaternary centers (3e: R1 = H, R2, R3 = -(CH2)5-; 3f: R1 = H, R2 = CH3, R3 = (CH2)2CH(CH3)2) may be formed in high yield and under mild conditions utilizing this protocol. The reaction is stereospecific and may be applied to the preparation of Delta(2,3)-beta-C-glycosides and alpha,beta-disubstituted lactones.

Treatment of allyl-1,1-dichlorovinyl ethers with n-BuLi at −78°C, followed by quenching with ketones, epoxides, and oxetanes, leads to highly substituted β-, γ-, and δ-lactones in good to excellent yields.

Exposure of dichlorovinyl ethers 1 to n-butyllithium and addition of saturated or unsaturated aldehydes, ketones, or esters at ambient temperature furnishes rearranged α,β-unsaturated carboxylic acids, isolated as their corresponding methyl esters 2 in 48–91% overall yields. Exposure of dichlorovinyl ethers 1 to n-butyllithium, addition of aldehydes, ketones, dialdehydes, or diketones at −78 °C, and warming to 80 °C in the presence of SiO2 provide 1,4-dienes 3 or cycloalken-1-ols (or their dehydration products) 4 in 45–72% overall yields.

Carboxylic acid esters P 0360Low-Temperature n-Butyllithium-Induced Rearrangement of Allyl 1,1-Dichlorovinyl Ethers. -The rearrangement occurs at low temperatures and under mild conditions to give high yields of products containing up to 2 new carbon-carbon bonds. The reaction is stereospecific and can thus be applied to the preparation of glycosides and α,β-disubstituted lactones. -(CHRISTOPHER, A.; BRANDES, D.; KELLY, S.; MINEHAN*, T.; Org. Lett. 8 (2006) 3, 451-454;

The BuLi‐mediated [3,3]‐sigmatropic rearrangement of allyl‐1,1‐dichlorovinyl ethers (I) and (XII) and subsequent quenching with ketones afford desired β‐lactones (III), (V), and (XIII) in moderate to high yields.