155876-95-2Relevant academic research and scientific papers
Intramolecular Reactivity of Arylcarbenes: 2-(Alkoxymethyl)phenylcarbenes
Kirmse, Wolfgang,Schnitzler, Dirk
, p. 1699 - 1702 (2007/10/02)
Both singlet and triplet states contribute to the intramolecular C-H insertion reactions of 2-(alkoxymethyl)phenylcarbenes, leading to dihydro-1H-2-benzopyrans.Competitively, oxygen ylides are generated which eventually give rise to benzocyclobutenes and dihydroisobenzofurans.The radical pair mechanism of the Stevens rearrangement is confirmed by variation of the alkyl groups and by means of chiral substrates.
Intramolecular Reactivity of Arylcarbenes: Derivatives of o-Tolylcarbene
Kirmse, Wolfgang,Konrad, Wolfgang,Schnitzler, Dirk
, p. 3821 - 3829 (2007/10/02)
Various CH2X groups have been attached to the ortho position of phenylcarbene.If 2'- or 3'-C-H bonds are present, as in 23 (X = Me), 71 (X = CMe3), and 58 (X = SiMe3), C-H insertion leading to five- or six-membered rings predominates in the gas phase and competes with intermolecular reactions in solution.The formation of benzocyclobutenes via insertion into 1'-C-H bonds is a very minor reaction path of 23 and 71.In contrast, 58 produces substantial amounts of the benzocyclobutene 59 by way of C-Si insertion, particularly in the gas phase.Insertion into the Si-Me bonds of 58 also occurs while the C-F bonds of 37 (X = CF3) and 50 (X = F) are inert.In the gas phase, 37 and 50 give mainly benzocyclobutenes whereas intermolecular reactions prevail in solution.The effects of sensitization and of solvent polarity suggest that benzocyclobutenes arise from singlet arylcarbenes.The amount of carbene-carbene rearrangement decreases in the order 7 (X = H) > 37 (X = CF3) > 23 (X = Me); no rearrangement was observed with 50 (X = F), 58 (X = SiMe3), and 71 (X = CMe3).
