Electronic modification of an aminotroponiminate zinc complex leading to an increased reactivity in the hydroamination of alkenes

Abstract

The electronically modified zinc complex 5-phenylsulfanyl-N-isopropyl-2-(isopropylamino)troponiminate zinc methyl, [(PhS-ATI(iPr)2)ZnMe], was synthesized. It showed an increased reactivity in the intramolecular hydroamination reaction of non-activated alkenes compared to a previously-reported, non-substituted complex.

Aminotroponiminatozinc(I) Complexes: Syntheses and Spectroscopic Analyses

“…[18] The zinc atoms in 1 and 2 adopt trigonal-planar geometries with Zn À N bond lengths of 2.02(2) and 2.02(2) (1) as well as 2.012(3) and 2.017(3) (2) , respectively, which are in the same range as observed for [{(iPr) 2 (3) ).…”

“…[16] In this context we were interested in preparing low-valent aminotroponiminato zinc-zinc bonded compounds. Reaction of the aminotroponimines N-isopropyl-2-(isopropylamino)troponimine [{(iPr) 2 ATI}H] [17] and 4-bromo N-isopropyl-2-(isopropylamino)troponimine [{4-BrA C H T U N G T R E N N U N G (iPr) 2 ATI}H] [18] with [(h 5 -Cp*) 2 Zn 2 ] in toluene at room temperature resulted in the formation of [{(iPr) 2 [20] in the 1 H NMR spectra of the complexes, and the IR spectrum had no absorption peak, which is in the typical range for Zn 2 H 2 four-membered-ring systems. [19] Crystals of 1 and 2 suitable for single-crystal X-ray diffraction analysis were obtained from a solution of 1 and 2 in toluene at À30 8C.…”

Transition‐Metal‐Catalyzed Hydroamination Reactions

“…The extensively investigated aminotroponiminate complexes of Zn [216] cocatalyst have been shown to mediate cyclohydroamination with gem-disubstituted secondary aminoalkenes to give five-membered ring products [275,276]. Modest ligand substitution effects have been noted (Table 15.24); however, the substrate scope disclosed for these systems displays previously noted limitations for a broad range of catalysts.…”

Recent progress in transition metal catalysed hydrofunctionalisation of less activated olefins

“…An electronically modified zinc complex 5-phenylsulfanyl-N-isopropyl-2-(isopropylamino)troponiminate zinc methyl, [{PhS-ATI(iPr)2}ZnMe], with zinc atom displays a trigonal planar geometry is showed an increased reactivity in the intramolecular hydroamination reaction of unactivated alkenes (Fig. 22 b) [58]. The thioether moiety at the backbone of the ligand acts as a donor substituent and therefore increases the electron density at the nitrogen and the zinc atoms.…”