Additions alkynes, palladium chloride

Alkenes can be converted to succinic esters by reaction with carbon monoxide, an alcohol, and palladium chloride in the presence of mercuric chloride.1,12 The addition is mostly syn. In similar reaction, both terminal and internal alkynes can be converted to esters of maleic acid. 

The conversion of acetylenes into olefinic esters by use of addition reactions has been illustrated by the following two examples, (i) 1-Alkenyl boranes, which are readily prepared by the hydroboration of alkynes, are converted into a,fi-unsaturated carboxylic esters in good yield by reaction with carbon monoxide in the presence of palladium chloride and sodium acetate in methanol the process is carried out at atmospheric pressure and occurs with retention of configuration with respect to the alkenyl borane. (ii) Carboxylic acids add to acetylenes in the presence of silver carbonate to provide a novel synthesis of enol esters, which are formed in an 8 2 mixture of isomers. ... 

Allyl chlorides can be employed in place of alkynes for the palladium-catalyzed [2-I-2-I-2] cycloaddition of arynes, as reported by Yamamoto et al. in 2000 [16]. Substituted allyl chlorides 40 reacted with aryne from 39 accompanying the elimination of HCl in the presence of a paUadium(0) catalyst and CsF to produce phenanthrenes 41 and 42 in good yields, although the regioselectivity was moderate (Scheme 6.13). A mechanism that has been proposed involves a cascade-type addition of -ir-allylpalladium complex onto two benzynes. In the presence of additional alkynes 44, three-component cycloaddition product 45 was obtained in good yields with complete regioselectivity (Scheme 6.14). 

Terminal alkynes react with propargylic carbonates at room temperature to afford the alka-l, 2-dien-4-yne 14 (allenylalkyne) in good yield with catalysis by Pd(0) and Cul[5], The reaction can be explained by the transmetallation of the (7-allenylpailadium methoxide 4 with copper acetylides to form the allenyKalk-ynyl)palladium 13, which undergoes reductive elimination to form the allenyl alkyne 14. In addition to propargylic carbonates, propargylic chlorides and acetates (in the presence of ZnCb) also react with terminal alkynes to afford allenylalkynes[6], Allenylalkynes are prepared by the reaction of the alkynyl-oxiranes 15 with zinc acetylides[7]. 

The groups R2N and Cl can be added directly to alkenes, allenes, conjugated dienes, and alkynes, by treatment with dialkyl-V-chloroamines and acids. " These are free-radical additions, with initial attack by the R2NH- radical ion. " N-Halo amides (RCONHX) add RCONH and X to double bonds under the influence of UV light or chromous chloride. " Amines add to allenes in the presence of a palladium catalyst. ... 

Support-bound stannanes have been prepared from phenyllithium bound to macro-porous polystyrene and chlorostannanes [14,41], by treatment of support-bound alkyl chlorides with lithiated stannanes [21,41], and by radical or palladium-mediated addition of stannanes to alkenes and alkynes (Figure 4.7 [42-47]). The chloride of poly-styrene-bound chlorostannanes can be displaced by treatment with arylzinc reagents, thereby yielding resin-bound arylstannanes [46]. Polystyrene-bound stannanes have also been prepared by copolymerization of 4-[2-(dibutylchlorostannyl)ethyl]styrene with styrene and divinylstyrene [48],... 

The activity of homogeneous catalysts tilso has been demonstrated Wiltan son s catalyst tns(tnphenylphosphine) rhodium chloride induces petfluoroalkyl iodides to add to olefins at 80 °C [10] (equation 10) Tetrakis(tnphenylphosphine)-palladium promotes the addition to both alkenes and alkynes in hexane [11] Amines and amine salts induce addition at 120-140 °C [12] (equation 11)... 

---