Diastereoselective Synthesis of Eight‐Membered‐Ring Allenes from Propargylic Epoxides and Aldehydes by Silylene Insertion into Carbon–Oxygen Bonds

Abstract

Bent out of shape: Silver-catalyzed insertions of silylenes into propargylic CO bonds of epoxides regioselectively form 1,2-silaoxetanes, which add to aldehydes to give the title allenes as single diastereomers (see scheme; Ts=4-toluenesulfonyl). An X-ray crystal structure confirmed the stereochemistry of the allene, which is bent significantly from linearity (164°).

Palladium‐Catalyzed Dehydrogenative Coupling Reaction of Terminal Alkynes with Unactivated Alkenes

“…Alkynyl epoxides are useful building blocks in organic synthesis . When the enyne 3a was treated with m CPBA, the alkynyl epoxide 6 was obtained in 83% yield (Eq.…”

Bisallylation of Zirconacyclopentenes and Ring-Closing Metathesis: A Route to Eight-Membered-Ring Compounds

“…The silyl ether was prepared according to procedure described by Woerpel. 2 Column chromatography of the residue on silica gel (hexanes) yielded 2.74 g (87 %) of the title product as a colorless liquid. The spectral characteristics are consistent with the reported data.…”