Reaction of (Z)-(Phenylvinyl)acetylenes and (Z)-(Cyclopropylvinyl)acetylenes with Fischer Carbene-Chromium Complexes: An Alternative Approach to Benzannulation and Cyclopentannulation

Abstract

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Group 6 Fischer carbene complexes: “chemical multitalents” for multi-component reactions

“…After ethylene extrusion takes place, the nature of the major component depends on the stability of enol ethers 92 towards hydrolysis [42] (Scheme 17). …”

“…Thus, the treatment of carbene complexes 1c with phenylalkenylacetylenes 95a or dienylacetylenes 95b usually leads to naphtofuran ketal derivatives 96 or to benzofurans 97, respectively, in good to excellent yields [42] (Scheme 18). In this occasion, the 1-metallahexatriene 98 generated after the alkyne insertion evolves, as in the Dö tz benzannulation, through intermediate 99 and further cyclization to 100.…”

1,3-Dien-5-ynes: Versatile Building Blocks for the Synthesis of Carbo- and Heterocycles

“…1). 136 In this case the six carbon atoms of the created aromatic ring include five coming from the dienyne skeleton and one coming from one of the carbonyl ligands of the Fischer carbene-chromium complex.…”

The [5+5] route to the phenanthrene skeleton

“…3 ) as surrogates for the coupling of simple alkynes with either α,β-unsaturated chromium carbene complexes 12 or cyclopropylcarbene complexes 13 in various cycloaddition reactions. 14 While looking intensely at this synthetic scheme for conjugated dienyne preparation a novel idea emerged. Making the requisite dienyne in all cases involved a Wittig reaction as the final step.…”