Formation of titanacyclobutenes with a spiro-bonded cyclopropane

Abstract

The reaction of titanium cyclopropylidene complexes, prepared by the reductive titanation of 7,7-dichlorobicyclo[4.1.0]heptanes, with alkynes produced air and moisture stable titanacyclobutenes with a spiro-bonded cyclopropane.

Toward a Silicon Version of Metathesis: From Schrock-Type Titanium Silylidenes to Silatitanacyclobutenes

“…Thus, a characteristic low-field resonance of +125.4 ppm was observed for the Ti-bound spiro-Si atom (calculated value 119.9 ppm). In the 13 C NMR spectrum of 3a , the olefinic carbons were observed at +104.7 ppm (Si-bound olefinic C) and +221.1 ppm (Ti-bound olefinic C), with the latter signal being a diagnostic feature of the titanacyclobutene derivatives (calculated values 103.9 and 218.5 ppm, respectively).…”

A new route to alkenylcyclobutenes

“…3 It is of interest that these strained titanacycles were thermally stable and could be isolated. In connection with this study, we examined the preparation of titanacyclobutenes having a cyclobutane substructure 1 by the reaction of internal alkynes 2 with titanium cyclobutylidene complexes 3, generated by the reductive titanation of cyclobutanone diphenyl thioacetals 4 with the titanocene(II) reagent Cp 2 Ti-[P(OEt) 3 ] 2 5.…”