Heck reactions 1,3-dipolar cycloadditions

Grigg and coworkers developed bimetallic domino reactions such as the electro-chemically driven Pd/Cr Nozaki-Hiyama-Kishi reaction [69], the Pd/In Barbier-type allylation [70], Heck/Tsuji-Trost reaction/1,3 dipolar cycloaddition [71], the Heck reaction/metathesis [72], and several other processes [73-75]. A first example for an anion capture approach, which was performed on solid phase, is the reaction of 6/1-134 and 6/1-135 in the presence of CO and piperidine to give 6/1-136. Liberation from solid phase was achieved with HF, leading to 6/1-137 (Scheme 6/1.30) [76]. 

Some interesting fused 1,2,3-triazole ring systems have been reported. A series of 5-piperidyl-substituted 7-hydroxy-3f/-l,2,3-triazolo[4,5-d]pyrimidines 143 has been synthesized from pipecolinate esters, benzylazides, and cyanoacetamide <06CHE246>. 4-Alkylidene-5,6-dihydro-4//-pyrrolo-[l,2-c][l,2,3]triazoles 144 were prepared from alkylidenecyclopropanes via diiodogenation/Cu(I)-catalyzed 1,3-dipolar cycloaddition/intra-molecular Heck reaction sequence <06SL1446>. 6,6-Dimethyl-2-phenyl-4,5,6,7-tetrahydro-27/-benzotriazol-4-one 145 were prepared from A-(5,5-dimethyl-3-oxocyclohexenyl)-S,S-diphenylsulfilimine and... 

Several routes to the pyrrolo[l,2-f][l,2,3]triazole skeleton have been described. Intramolecular dipolar cycloaddition of azido-alkenes or alkynes seems to be the most convenient process, although the cyclization efficiency seems to be highly substrate dependent (Scheme 16) <2002JA2134, 2003T1477, 2005SL2187, 2005TL8639>. The formation of this bicyclic system by an intramolecular Heck reaction is an attractive alternative. The recent syntheses of sulfamides by intramolecular cyclization of alkenes or allenes offer a complementary route to the classical... 

Another gain in diversity is achieved by the combination of these cross couplings with uncatalyzed reactions. Because of their oligounsaturated character, the coupling products are obviously well suited for subsequent peri-cyclic reactions leading to additional cyclizations. These atom-efficient processes are especially attractive since they typically proceed with high chemo-, regio- and stereoselectivity [18]. This review is intended to cover Heck reactions and related palladium-catalyzed processes followed by Diels-Alder reactions, 1,3-dipolar cycloadditions or 6 -electrocyclizations. 

Grigg, R., Millington, M.L. and Thomton-Pett, M. (2002) Spiro-oxindoles via bimetallic [Pd(0)/Ag(l)] catalytic intramolecular Heck-1,3-dipolar cycloaddition cascade reactions. Tetrahedron Lett., 43, 2605-8. 

---