Studies on the intramolecular Kulinkovich–de Meijere reaction of disubstituted alkenes bearing carboxylic amide groups

Abstract

1,2-Disubstituted olefins bearing an acetamide group were found to undergo intramolecular Kulinkovich-de Meijere cyclopropanation in moderate yield but almost complete diastereoselectivity.

Electrochemical Aerobic Oxidation of Aminocyclopropanes to Endoperoxides

“…After cyclopropane ring opening, reaction with oxygen, and ring closure, the newly produced cation radical would be able to function as an oxidant itself and thus close the catalytic cycle (Scheme 1). [4,5] Although interesting, this reaction suffers from serious limitations: a) the transformation appears to be facile only in the special cases where the nitrogen atom bears a hydrogen atom or an electron-rich aromatic ring; b) the use of peroxides under UV irradiation is by nature limited to secondary amines because it involves hydrogen abstraction from the nitrogen atom; c) the iron(III) catalyst mentioned above is not commercially available; and d) occasionally experiencing problems in isolating the expected peroxides, we were led to suspect that some of them might be unstable. [6] We anticipated that electrochemical methods such as cyclic voltammetry and preparative electrolyses would be tools of choice to gain better insight in this reaction and could lead to the design of a more general and environmentally friendly experimental procedure.…”

“…A similar transformation was observed in our laboratory, spontaneously occurring in the presence of air and silica gel from electronrich tertiary arylcyclopropylamines. [5] In this case, as well as in the iron-catalyzed process, the mechanism probably involves a one-electron oxidation of the substrate to a cation radical intermediate. After cyclopropane ring opening, reaction with oxygen, and ring closure, the newly produced cation radical would be able to function as an oxidant itself and thus close the catalytic cycle (Scheme 1).…”

Titanium-mediated syntheses of cyclopropylamines

“…1,2-Disubstituted alkenes bearing an acetamide group were found to undergo intramolecular cyclopropanations in low or moderate yield, but almost complete diastereoselectivity [87].…”

“…Aminocyclopropanation of 1-ethenylcycloalkenes 34. [73,[82][83][84][85][86][87]. For further details see Table 5.…”

“…These aminocyclopropanations of terminal alkenes can also be applied intramolecularly in several versions [74,[82][83][84][85][86][87]. Terminally, ethenyl-substituted N ,N -dialkylcarboxamides like 37 yield 1-(dialkylamino)bicyclo[4.1.0]alkanes like 38 [74,82], while (x-alkenylamino)carboxamides like 39 lead to 1-alkyl-2-azabicyclo[(n þ 3).1.0]alkanes like 40 [83,87], and N -allylaminoacid N ,N -dialkylamides 41 furnish bicyclic diamines 42 [84][85][86] (Scheme 10, for selected examples see Table 5).…”