Ring‐opening reactions of 3‐substituted 1‐azabicyclo[1.1.0]butane with dichlorocarbene

Abstract

Reaction of 3‐ethyl‐1‐azabicyclo[1.1.0]butane (1a) with chloroform‐potassium tert‐butoxide afforded a ring‐opened product, 1,1‐dichloro‐2‐aza‐4‐ethylpenta‐1,4‐diene (4a), which was characterized via conversion to the corresponding N‐substituted 5‐chloro‐1,2,3,4‐tetrazole, Sa. Reaction of 3‐phenyl‐1‐azabicyclo‐[1.1.0]butane (1b) with “Seyferth's reagent” (PhHgCCl2Br) afforded 1,1‐dichloro‐2‐aza‐4‐phenylpenta‐1,4‐diene (4b), which also was characterized via conversion to a tetrazole derivative, i.e., 5b. Finally, the reaction of 1b with dichlorocarbene generated under phase transfer conditions (chloroform‐sodium hydroxide‐TEBA) was studied. At short reaction times (0.5 hour), the major reaction product was 4b. However, at longer reaction times (20–30 hours), two secondary products, 8 and 9, were formed which resulted via subsequent dichlorocyclopropanation of 4b.

Reactions of N-(Ethoxycarbonyl)-3-halo-3-(halomethyl)azetidines with DBU. The Halogen Dance

“…However, the current decade has witnessed a renaissance of interest in azabicyclo[1.1.0]butane chemistry . Thus, reactions of carbenes and a variety of other electrophiles , with 3-substituted 1-azabicyclo[1.1.0]butanes have been reported recently. In addition, their use as intermediates in the synthesis of energetic materials, e.g., 1,3,3-trinitroazetidine (TNAZ) in particular, has been reported .…”

N-Functionalized Benzotriazole-1-carboximidoyl Chlorides: Synthetic Equivalents for Isocyanide Dichlorides

“…Isocyanide dichlorides, including N -acyl and N -sulfonyl derivatives, undergo nucleophilic substitution with various nucleophiles to provide access to carbodiimides, guanidines, chloroformamidines, thioesters, isoureas, isothioureas, carbonimidates, and five- and six-membered heterocycles . Preparative routes to isocyanide dichlorides include (i) the reaction of isothiocyanates with chlorine, (ii) the reaction of isocyanates with phosphorus pentachloride,5a (iii) the addition of chlorine to isocyanides, , (iv) the reaction of monosubstituted formanilides with a mixture of thionyl chloride and sulfuryl chloride, (v) the addition of dichlorocarbenes to azides or azabicyclobutanes, and (vi) the reaction of trisubstituted ureas with carbon tetrachloride in the presence of triphenyl phosphine or with phosphorus pentachloride . While many isocyanide dichlorides can be made in satisfactory yields by these methods, these compounds are often strongly corrosive, toxic, and sensitive toward hydrolysis, , properties that decrease their convenience for possible applications.…”