Allenes thiocarbonylation

Besides alkoxy-, amino-, and amidocarbonylation reactions, a carbonylation process using a thiol as nucleophile, that is, thiocarbonylation, has been extensively studied.It has been shown that the thiocarbonylation takes place with 1-alkynes, " " " propargyl alcohols,allenes, " 1,3-dienes, propargylic mesylates, " and bicyclopropylidene . 

Alkylaminocarbonyl- -dialkylester XII/2, 43 Alkvlamino-thiocarbonyl- -dialkylester XII/2, 43 aus Phosphorigsaure-dialkylester und Isothio-cyanat allgemeine Arbeitsweise XII/1, 458 Alkylthio-carbonyl- -dialkylester XII/2, 43 Alkylthio-cthin- -dialkylester E2, 373 Alkylthio-thiocarbonyl- -dialkylester XII/2, 43 Allen- -dichlorid E2, 326... 

Dithiins 367 have been prepared in moderate yields by [4 + 2] cycloaddition of in situ formed thioenones with thiocarbonyl groups (Scheme 171) <2004SL2159, CHEC-III(8.11.9.2)824>. The thio compounds were generated from trialkylsilyl- or trialkylstannyl-tetrahydropyranyloxy allenes 366 using bis(trimethylsilyl)sulfide (HMDST) and CoC nbE O. 

The photocycloaddition of thiocarbonyl-containing compounds to alkenes provides an easy route to thietanes. 2,4,6-Tri-(t-butyl)thiobenzaldehyde (249) undergoes regiospecific addition to substituted allenes (250) to give the vinyl-thietanes (251). The formation of the ketones (252) by irradiation of the aryl... 

On the other hand, thiocarbonylation of simple allenes such as 119 with ben-zenethiol afforded the -unsaturated thioester 120 in good yield. Attack of CO at the terminal carbon occurred. Somewhat unexpectedly, thiocarbonylation of methoxyallene 113 also took place at the C-3 carbon to give the thioester 121 [37]. 

By Cycloadditions involving Thiocarbonyl Compounds. The photocatalysed cycloaddition of thiocarbonyl compounds to olefins to form thietans has been reviewed. The photo-addition of thiobenzophenone to cis- and /m j-dichloroethylene and to cw-dicyanoethylene apparently proceeds with retention of configuration in the olefin moiety. Allenes participate in such reactions, thiobenzophenone with tetramethylallene > and methoxy-allene, for example, giving the thietan derivatives (44) and (45). Thiobenzophenone in its triplet excited state apparently attacks the central... 

TABLE 2. Pd-Catalyzed Thiocarbonylation of Allenes with Thiols"... 

The process of transfer of one hydrogen atom from an allylic alkene (an ene) to an electrophilic alkene (an enophile) followed by formation of a new cr-bond and migration of allylic double bond is known as ene reaction or Alder ene reaction [1]. The ene may be an alkene, alkyne, allene, cyclopropane ring or arene, whereas an enophile may be an alkene, carbonyl, thiocarbonyl, imino or diazo compound having an electron withdrawing substituent. Oxygen may also serve as an enophile. The reaction usually takes place from left to right, since a new [Pg.161]

The cumulenes discussed in this book are subdivided into carbon- and noncarbon cumulenes, and the 1-carbon cumulenes (sulfines, sulfenes, thiocarbonyl S -imides and thiocar-bonyl S -sulfides) are excellent dipolar species. The 2-carbon or the center-carbon cumulenes (carbon dioxide and carbon sulfides) are less reactive but their imides (isocyanates, isothiocyantes and carbodiimides) readily participate in many of the discussed reactions. The 1,2-dicarbon cumulenes (ketenes, thioketenes and ketenimenes) similarly participate in cycloaddition reactions, as well as the more exotic 1,2-dicarbon cumulenes (1-silaalene, 1-phosphaallene and other metal allenes). In contrast, 1,3-dicarbon cumulenes are only... 

Xiao W, VasapoUo G, Alper H. Highly regioselective palladium-catalyzed thiocarbonylation of allenes with thiols and carbon monoxide. J. Org. Chem. 1998 63 2609-2612. 

Allenes also undergo highly regioselective thiocarbonylation with thiols and carbon monoxide in the presence of palladium catalysts. The use of Pd(OAc)2/PPh3 as the catalyst leads to the selective formation of p,y-unsaturated thioesters (Scheme 34) [115]. 

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