Lithium–Titanium Exchange of Tertiary α‐Sulfonyl Carbanions: Synthesis, Structure, Dynamics and Reactivity of Bis(1‐sulfonylalkyl)titaniums

Abstract

AbstractLithium–titanium exchange of tertiary α‐sulfonyl carbanions with ClTi(OiPr)3 and Cl2Ti(OiPr)2 in diethyl ether gave bis(1‐sulfonylalkyl)titaniums and not the corresponding (1‐sulfonylalkyl)titaniums. X‐ray crystal structure analysis of di(isopropoxy)bis[1‐(phenylsulfonyl)cyclobutyl]titanium and di(isopropoxy)bis[1‐(phenylsulfonyl)isopropyl]titanium showed asymmetric distorted octahedral complexes, having hexacoordinate Ti atoms, two C–Ti bonds, four Ti–O bonds, and two four‐membered Ti–O–S–Cα rings. According to 1H NMR spectroscopy bis(1‐sulfonylcycloalkyl)titaniums are non‐fluxional at room temperature. This suggests that chiral bis(1‐sulfonylalkyl)titaniums should be configurationally stable. The bis(1‐sulfonylalkyl)titaniums are stable at room temperature towards β‐H elimination. They selectively add to benzaldehyde in the presence of acetophenone but do not react with methyl iodide. The reaction of tertiary acyclic α‐sulfonyl carbanions with ClTi(OiPr)3 in tetrahydrofuran (THF) gives different titanium derivatives with unspecified structures, which not only selectively react with benzaldehyde in the presence of acetophenone but are also alkylated by methyl iodide.