911. A new reaction of aliphatic diazo-compounds

Abstract

showed that aliphatic diazocompounds do not combine with tertiary amines as they do with phosphines; diphenyldiazomethane when heated with triethylamine undergoes the same decomposition to benzophenone azine as when heated in other solvents. If the first product of decomposition of the diazo-compound is the uncharged diphenylmethylene radical Ph&, it is conceivable that this will co-ordinate, reversibly, with the amine, giving Ph,C-NEt,, although in the end its fate is to combine with unchanged diazo-compound, yielding the azine. A case might then be found in which the dipolar ion would be stable or would undergo irreversible change to a significant product. We failed to effect the combination of diazofluorene with fluorenone methylimine to give the specially stabilised compound (I) ; -+ c but diazofluorene and benzyldimethylamine afforded a considerable amount of 9-benzyl-9dimethylaminofluorene (11). Wittig and Felletschin (Annalen, 1944, 555, 133) obtained the same compound from (111) via the unstable (IV).

Bamford‐Stevens and Shapiro Reactions in Organic Synthesis

“…In the 1952 article, Bamford‐Stevens proposed a plausible mechanism for the reaction, which is widely accepted now [1] . It was supposed that the diazo‐compound is always a primary product, as shown in Figure 1.…”

“…Bamford‐Stevens reaction was discovered in 1952 [1] . It was developed based on earlier results published by Escales who found that benzenesulphonylphenylhydrazide decomposes to benzene after treatment with warm alkali [2] .…”

Eco-Friendly Approach to Tetrasubstituted Diazodihydrofuran­ones: Valuable Precursors of Oxetane Derivatives and Other Heterocyclic Compounds

“…The second series of diazoketones 2a-e was prepared using a modified approach, which involved nitrosation 21 of monoketones 6a-e followed by conversion of the resulting α-diketones 7a-e into tosylhydrazones 9a-e accompanied by the Bamford-Stevens reaction. 7,22 Nitrosation of ketones 6a-e was carried out with sodium nitrite in the presence of concentrated hydrochloric acid. In fact, it involved a two-stage process -initial formation of oximes 10a-e followed by their hydrolysis under the reaction conditions to furnish α-diketones 7a-e.…”

“…The final stage of the synthesis of diazoketones 2a-f was the Bamford-Stevens reaction, which usually involves alkaline cleavage of 4-toluenesulfonyl hydrazones at elevated temperatures with strong bases, such as metal alkoxides, and others. 7,22 This process does not often stop at a stage of formation of diazo compounds, but leads to their decompo-sition with formation of by-products -alkenes, N-alkylated tosylhydrazones, etc. -generated via intermediate carbenes and/or carbenium ions.…”

Reactions Involving Hetero Atoms

“…Treatment of diaryldiazoalkanes with haloforms and base afforded azines [21] and alkenes [22] in variable amounts (59). Only alkenes [24] were obtained from organophosphorussubstituted diazoalkanes [23] with the dihalocarbenes generated from PhHgCCl 2 Br, PhHgCClBr 2 , and PhHgCBr 3 (60). The base-induced elimination of HX from derivatives of ethynylcarbinols (Chapter 4, Section V) in the presence of diaryldiazomethanes produced the corresponding cumulenes in 5-26% yield (60a).…”