Time-resolved flash spectroscopic investigations of the reactions of singlet arylhalocarbenes

Distortion/interaction analysis of the reactivities and selectivities of halo– and methoxy–substituted carbenes with alkenes

“…We found that favorable interaction energy contributes to negative ∆E at intermediate separation of the carbenes and alkenes studied here and suggests the formation of carbene-alkene precursor complexes, although the existence of these has been debated in the literature. [20][21][22][23][24][25][26][27][28][29] We have confirmed π-complexes for cycloadditions to 2a, 2b, and 2d that are stabilized by 0-5 kcal mol…”

Persistent Triplet Carbenes

“…The desired diazomethanes (81c-d 12 -N 2 and 81c-d 8 -N 2 ) were prepared, and product analysis as well as kinetic studies was carried out. Irradiation of 81c-d 12 -N 2 in benzene at 15°C produced the carbenic dimer (82c-d 24 , 73%) as a main product at the expense of the cyclobutene (83c-d 12 , 27%) (Scheme 14). This is in sharp contrast with that observed for 81c, which produced the cyclobutene almost exclusively.…”

Interconversion of Electronic Spin State of p-Substituted Arylketocarbene Reactions

“…[20][21][22] Therefore it is necessary to identify a clear-cut photolytic experimental results. Most cases 14,15,23,24 show there are different electronic spin-state in accordance with producing from diazirine derivatives or diazo derivatives as shown in Scheme 6.…”

“…11 Generally, alkylcarbenes give ylide intermediates, 7 in their trapping compounds as acetonitrile or pyridine. [12][13][14][15][16][17] Although many alkylketocarbene reactions with acetonitrile or pyridine quenchers have been studied, the ylide intermediates involving arylketocarbene with acetonitrile or pyridine have not yet reported.…”

“…[8][9][10][11][12][13][14][15][16][17][18][19] Generally it is well known that photolysis of alkyl carbomethoxy carbene gives a product of triplet sensitization. Triplet sensitization lowers the yield of the product abstracted from singlet carbene as well as the yield of the product of C-H insertion.…”