Alkatrienyl Sulfoxides and Sulfones. Part VI. Cheletropic Addition of Sulfur Dioxide to 1- and 3-Vinylallenyl Sulfoxides and Sulfones

Regio- and stereoselective Diels-Alder reaction of diphenyl 5-methylhexa-1,3,4-trien-3-yl phosphine oxide with N-(4-substituted-phenyl)maleimides and maleic anhydride

“…Although the exact mechanistic aspects of this transformation have not been rigorously elucidated, the following pathway could be a probable stereochemical route on the basis of experimental results as illustrated in Scheme 3. Hz and 9.0 Hz in the 1 H NMR spectra of cyclic products 3a-g and 5 respectively, approve the syn-position of the corresponding protons 25,44 .…”

“…In view of the advantages of vinylallenes as the diene component in [4+2] cycloaddition reactions [23][24][25][26][27][28][29][30][31][32][33][34][35] and our results on the cycloaddition reactions of vinylallenyl sulfoxides and sulfones [39][40][41][42] with dimethyl but-2-ynedioate 43 and maleic anhydride 45 as well as on the cheletropic addition of sulfur dioxide 44 to them, we therefore continued a study of the use of the diphenyl 5-methylhexa-1,3,4-trien-3-yl phosphine oxide 37 in the Diels-Alder reaction with N-(4-substituted-phenyl)maleimides and maleic anhydride. The results of this work are presented here.…”

From Allylic Sulfoxides to Allylic Sulfenates: Fifty Years of a Never-Ending [2,3]-Sigmatropic Rearrangement

“…The versatile reactivity of allenyl sulfoxides and their easy access from propargylic sulfenates using [2,3]-sigmatropic rearrangement have made them ubiquitous synthetic intermediates that evolve through desulfinylation with n-BuLi, 278 desulfinylation by electrophilic addition of iodine to the allene, 279 α-deprotonation followed by alkylation, 280 γ-deprotonation, 271,281 chelotropic addition of SO 2 , 282 and Michael nucleophilic additions to the allene central carbon of amines, 283 alcohols, 284 sulfides, and dimethyl cuprate. 285 In particular, allenyl sulfoxides 468 and 474, prepared from propargylic alcohols 467 and 472, respectively, contain internal nucleophiles and provide simple access to heterocyclic structures such as spiroketals 470 286 and indoles 475 (Scheme 81).…”

“…In particular, Christov and Ivanov reported that enynol 476 is transformed into allenyl sulfoxide 478 through sulfenate−sulfoxide rearrangement of sulfenate 477 by treatment with PhSCl and Et 3 N. Further electrophilic addition of bromine to the allene double bond provided an 87% yield of oxathiolium bromide 479, which underwent ring cleavage by HBr elimination upon refluxing in dichloroethane to generate triene sulfoxide 480 in 61% yield (Scheme 82). 288,289 Cyclization with PhSCl, SO 2 Cl 2 , or PhSeCl provides comparable yields. In contrast, when the ester group is attached to the allenyl sulfoxide (483), ring closure takes place by nucleophilic assistance of this group, allowing for the synthesis of 2,5-dihydrofuranones 484.…”

Bifunctionalized Allenes. Part XVI. Synthesis of 3-Phosphoryl-2,5-dihydrofurans by Coinage Metal-Catalyzed Cyclo-isomerization of Phosphorylated α-Hydroxyallenes

“…Our long-standing research program focuses on the development of efficient cyclization reactions of 1,1- [ 50 , 51 ] and 1,3-bifunctionalized allenes [ 52 , 53 ]. More specifically, our attention is drawn to phosphorylated hydroxyallenes as 1,1-bifunctionalized allenes that comprise a phosphoryl and a hydroxyalkyl group.…”