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Lithium–Titanium Exchange of Tertiary α‐Sulfonyl Carbanions: Synthesis, Structure, Dynamics and Reactivity of Bis(1‐sulfonylalkyl)titaniums
Author(s) -
Heß Thomas,
Raabe Gerhard,
Gais HansJoachim
Publication year - 2014
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201402896
Subject(s) - chemistry , acetophenone , carbanion , benzaldehyde , sulfonyl , methyl iodide , medicinal chemistry , methyllithium , iodide , titanium , reactivity (psychology) , lithium (medication) , alkylation , organic chemistry , catalysis , medicine , alkyl , alternative medicine , pathology , endocrinology
Lithium–titanium exchange of tertiary α‐sulfonyl carbanions with ClTi(O i Pr) 3 and Cl 2 Ti(O i Pr) 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–C α rings. According to 1 H 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(O i Pr) 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.