Cyclo experimental procedures

Deoxyiodination has been used for the synthesis of 17 (n = 4). ° For the preparation of bi-cyclo[1.1.0]butane 17 (n = 1) and congeners thereof, special conditions are required. Reaction of l-bromo-3-chlorocyclobutane with sodium in refluxing dioxane gave bicyclo[l. 1. OJbutane in 90% yield a detailed experimental procedure is given.Hexamethylbicyclo[l, 1.0]butane was similarly obtained in 75% yield using sodium-potassium alloy in 1,2-dimethoxyethane. ... 

The cycHc urea moiety provides structural rigidity as well as hydrogen-bonding possibihties similar to those of the imidazoles described above. The corresponding 2-imidazolones have been prepared on a soHd phase by tandem aminoacylation of a resin-bound allylic amine with an isocyanate followed by intramolecular Michael addition [73]. However, due to the paucity of data presented on the characterized compounds and the brief experimental procedure, this synthesis is not discussed in detail. Access to cyclic ureas or thioureas has also been obtained by reaction with carbonyl- or thiocarbonyldiimidazole through a cyclo-release mechanism [74—76]. 1,3-Dihydroimidazolones have been obtained by treatment of ureido acetals with TFA and subsequent conversion in an intramolecular cyclization via an N-acyliminium ion [77]. 

In the usual experimental procedure, an acidic salt is first complexed with base and then treated with cyclopentadiene which reacts to form the cyclo-pentadienyl metal compound. The by-product salt is separated from the cyclopentadienyl metal compound by extraction with water. 

An improved experimental procedure for the synthesis of cyclobutanones via cycloaddition of dichloroketen gives good yields, even with hindered olefins. Hassner and Dillon have applied their method for in situ generation of dichloroketen to the conversion of acetylenes [e.g. (35)] into dichlorocyclo-butenones [e.g. (36)]. The 2-exomethylenecyclobutanone (39) is readily prepared from (38), the adduct of the 2-thiophenylketen (37) with cyclo-pentadiene. ... 

Recently, Roy et al. [23] reported the synthesis of mesoionic derivative and probable mechanistic feature of its derivatives. In this report we have tried to establish the experimental observation by theoretical model. We have first tried to establish the mechanistic pathway of the cyclo-addition procedure in terms of the computed local reactivity descriptors like fukui functions, local softness and local philiciy indices. 

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