Gold(I)‐Catalyzed 1,4‐ and/or 1,5‐Heteroaryl Migration Reactions through Regiocontrolled Cyclizations

Abstract

Gold(I)-catalyzed regioselective cycloisomerizations of furan-ynes have been described. The reaction provides a concise access to stereodefined trisubstituted alkenes by endo cyclization with concomitant 1,5-migration of the furanyl group in the presence of unactivated 3 Å molecular sieves. In the absence of molecular sieves, indene products are generated by exo cyclization, followed by 1,4-furanyl migration/cyclization. The scope for 1,5-migrations can be extended to other heterocycles, such as benzofurans, thiophenes, and pyrroles.

Chirality Transfer in Gold(I)‐Catalysed Direct Allylic Etherifications of Unactivated Alcohols: Experimental and Computational Study

“…Removing molecular sieves from the reaction results in a completely racemic product 5 db and a poor 3:1 E / Z ratio (vs. 89:11 e.r. and 9:1 E / Z with molecular sieves added) 21…”

Gold(I)-Catalyzed Activation of Alkynes for the Construction of Molecular Complexity

“… 390 It has been recently described that the same substrates undergo an endo -selective cyclization with concomitant 1,5-migration of the furan group in the presence of unactivated molecular sieves to yield trisubstituted alkenes 436 (Scheme 142 ). 391 …”

Catalytic Gold Chemistry: From Simple Salts to Complexes for Regioselective C−H Bond Functionalization

“…Although not a CÀ H functionalization reaction, it is quite interesting to note that replacing TBS by a TMS group devoid of hydrogen on the benzylic site (R 2 = H) 286, led to the formation of regiodivergent products. [257] Under sealed conditions in toluene, indene derivatives 287 were formed by 1,4-furanyl migration via 5-exo-digcyclization. Conversely, the same reaction in presence of unactivated molecular sieves (3 Å) and Ph 2 SO (20 mol%) generated alkenated products 288 through a 1,5-furanyl migration (via 6-endo-dig attack) followed by hydrolysis (Scheme 50,Eq.…”

“…The exclusive endo ‐type cyclization in this reaction pathway was rationalized by the formation of stable aromatic naphthyl rings. Although not a C−H functionalization reaction, it is quite interesting to note that replacing TBS by a TMS group devoid of hydrogen on the benzylic site (R 2 =H) 286 , led to the formation of regiodivergent products [257] . Under sealed conditions in toluene, indene derivatives 287 were formed by 1,4‐furanyl migration via 5‐ exo ‐ dig cyclization.…”