Allenes sulphonyl

The free radicals produced by the irradiation of the sulphonyl iodides can also be trapped by double bonds in a reaction akin to those described for the sulphonyl chlorides (Section I.A). Thus the irradiation of p-toluenesulphonyl iodide (11a) in the presence of acrylonitrile and butadiene affords the adducts 15 and 16, respectively. In the absence of an alkene or diene, irradiation affords the anhydride 17 and the disulphone 1826. Truce and coworkers27 have also utilized this reaction mode in a study of the light-induced addition of sulphonyl iodides to allenes. 

Semi-empirical INDO calculations have been carried out on cycloheptatrienyli-dene, cycloheptatetraene, and related systems. The most stable structure for cyclo-heptatetraene was found to be non-planar with a C2 axis of symmetry, and should be more stable than the carbene form. Even though most of the chemistry of cyclo-heptatrienylidene is consistent with carbene behaviour, the allene and carbene forms may be in equilibrium, and the position of equilibrium solvent-dependent. In fact decomposition of the sodium salt of the toluene-p-sulphonyl-hydrazone (163) gives dimeric products formed from allene (164), and addition of cycloheptatrienylidene to tetracyclones gives products derived from the adduct (165). ... 

Other Reactions of Allenes.— Radical-chain additions to allenes are presumed to involve radical intermediates of allylic structure by initial attack at the central carbon atom or of vinylic structure by attack at the terminal carbons. The extent to which these structures are preferred depends upon structure of starting allene, nature of attacking radicals, and reaction conditions. Addition of toluene-/ -sulphonyl iodide to chiral allenes (cyclonona-1,2-diene and penta-2,3-diene) results in racemic products (376), and hence attack on... 

Protonation of the allenyl complex (16) with HPFg at — 20°C gives the cationic acetylene complex (17), and this observation, together with product stereochemistry, strongly suggests that the [2 + 3] cycloaddition reactions of (16) with tetracyanoethylene and toluene-p-sulphonyl isocyanate, which generate (18) and (19), respectively, proceed via an acetylene dipolar ion (20) rather than an allene (21). However, protonation of the related butynyl complex (22) generates stereospecifically a cationic allene complex (23), which on... 

Allenic sulphoxides ArSOCH=C==CR R are available through the reaction of sulphenyl halides with propargyl alcohols HC CCR R OH. Friedel-Crafts reactions with toluene>p-sulphinyl chloride in the presence of AICI3, SnCh, or SbCl, give aryl p-tolyl sulphoxides, and an analogous product is obtained unexpectedly, using toluene-p-sulphonyl chloride with isoquinoline as substrate in the presence of excess NaH. ... 

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