Manganese carbonyl-mediated reactions of azabutadienes with phenylacetylene, methyl acrylate and other unsaturated molecules

Abstract

SynopsisPhCH 2 Mn(CO) 5 reacts with 1,4-di-aryl-1-aza-1,3-butadienes in the presence of unsaturated substrates to give products based on a cyclomanganated intermediate.PhCH 2 Mn(CO) 5PhC CH PhNCO CH 2 =CHCOOMe CO 2 Abstract.Reaction of PhCH 2 Mn(CO) 5 with 1,4-di-aryl-1-aza-1,3-butadienes gave substituted pyrrolinonyl rings which were 4 -coordinated to a Mn(CO) 3 group. These are formed by intramolecular CO insertion into a (non-isolated) cyclomanganated intermediate, followed by cyclisation. Other unsaturated reagents (PhC>CH, CH 2 =CHCOOMe, PhNCO) gave products arising from insertion of these, including a structurally characterised tri-aryl-5 -azacyclohexadienyl-Mn(CO) 3 complex from the reaction with the alkyne.

Cyclorhenated compounds derived from 1,4-diaryl-1-azabutadienes: preparation, structures and reactions

“…The manganese analogue of 9 was prepared from an in situ reaction of PhCH 2 Mn(CO) 5 , diphenylazabutadiene and PhCCH and was assumed to involve the intermediacy of the cyclometallated compound 1, which was not directly observed [3]. The isolation of the rhenium complex 9 from a cyclometallated precursor under comparable conditions supports this previously suggested pathway.…”

“…4. The crystals are isomorphous with the manganese example reported earlier [3]. The C(4)-C(8) atoms are essentially planar, forming a dihedral angle with the C(4)-N(1)-C(8) plane of 48.7°(50°for the Mn analogue).…”

“…It appears that first-formed 3 underwent spontaneous CO-insertion and cyclisation under the cyclometallation conditions. In situ reactions of the putative 3 as it formed, with alkynes or alkenes, gave products consistent with initial cyclomanganation [3]. Homrighausen et al have reported some complexes of type 3 from an indirect route [4].…”

“…When a mixture of 1,4-diphenyl-1-azabutadiene and PhCH 2 Re-(CO) 5 was heated under reflux in heptane, the resulting red mixture provided two major products after chromatography. The first of these was yellow and was characterised as the cyclorhenated complex 4a, the rhenium analogue of the implicated manganese metallocycle 3a that could not be isolated in the previous investigation [3]. This was apparent from the microanalytical and mass spectrometry data, and also from the m CO bands which conformed to the usual pattern found for cis-L 2 M(CO) 4 species.…”

“…We have previously described the preparations of cyclomanganated species from enones (chalcones), 1, and shown that their reactivity differs from that of cyclomanganated acyl-arenes [2]. As an extension of this work we investigated the manganese chemistry of related azabutadienes, 2 [3].…”