Carbon dioxide alkenes/alkynes with

Carbon dioxide reacts either with alkene and alkyne complexes of nickel(0) or with free alkenes and alkynes in the presence of nickel(O) complexes, giving five-membered cyclic nickel(II) complexes (equations 90 and 91).278... 

The photoelimination of carbon dioxide from esters and lactones is a process that has been the subject of detailed investigations. Discussion here is limited to nitrogen containing systems. 3,4-Diphenylsydnone (464), on irradiation in benzene, is converted via the nitrile imine 465 into 2,4,5-triphenyl-1,2,3-triazole (466)388 initial bond formation between N-2 and C-4 followed by loss of carbon dioxide to give the diazirine 467 is proposed to account for the formation of the nitrile imine. Nitrile imines generated in this way have been trapped with alkenes and alkynes to give pyrazoles389... 

Recently, the conversion of alkenes or non-activated internal alkynes into the corresponding carboxylic acids and/or butenolides has been achieved through carboxylation of titanacycle intermediates of type 73 with carbon dioxide (Scheme 27).78... 

A The alkynyl hydrogen of propyne is acidic and hence the propyne will form an organometallic derivative. The Grignard derivative will react with carbon dioxide to give the carboxylic acid. Cis alkenes are formed by the catalytic hydrogenation of alkynes using a Lindlar catalyst. Hence a propynyl alcohol is a precursor to compound (b). This could be obtained by the addition of a propyne anion to propanone ... 

Phenylsydnone is the prototype of that class of mesoionic compounds called sydnones. On acidic hydrolysis it produces phenylhydrazine, whereas basic hydrolysis regenerates N-nitroso-N-phenylglycine. This sydnone undergoes a variety of electrophilic substitutions,3,4 8-19 including mercuration n-13,16 and formylation,19 with an ease comparable to thiophene, and a number of 1,3-dipolar cycloadditions with numerous alkenes,18 18 alkynes,17 and quinones8 to form, with loss of carbon dioxide, a variety of pyrazole derivatives. 

ABSTRACT The review covers particularly the synthesis of fine chemicals via the formation of C-C bonds between carbon dioxide and hydrocarbons. In the reactions of CO2 with alkenes, dienes and alkynes a great number of carboxylic acids, dicarboxylic acids, esters, lactones and pyrones are formed, whether in stoichiometric or catalytic reactions. In each chapter the reactions are considered in the order of the transition metals applied. In addition, some syntheses will be mentioned which are closely related to transition metal catalysis, for instance the electrocarboxylation ofolefinic hydrocarbons. 

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