The copper(I)-catalyzed regioselective [3 + 2] cyclization of pyridines toward alkenyldiazoacetates leading to functionalized indolizine derivatives is reported. A broad range of pyridine derivatives (including quinoline and isoquinoline) is compatible with this cyclization reaction. The process represents the first successful example of metal-catalyzed cyclization of a π-deficient heterocyclic system with alkenyldiazo compounds.

The reaction of nitriles with alkenyldiazo compounds in the presence of gold catalysts provides functionalized pyrrole derivatives in moderate to high yields. This formal [3+2] cyclization reaction takes place with complete regioselectivity. The observed regiochemical outcome suggests the attack of the nitrile to the terminal position of the alkenylgold carbenoid (vinylogous reactivity). A broad range of nitriles (including those bearing functional groups) is compatible with this cyclization reaction.

The copper(II)-catalyzed reaction of alkenyldiazo compounds with iodosylbenzene leading to β-oxodiazo derivatives is reported. This process occurs via an unprecedented 1,2-shift of the diazoacetate function. A selection of the synthetic applications of a representative member of this new class of functionalized diazo derivatives in the regioselective synthesis of substituted 1,4-dicarbonyl compounds is also reported.

A convenient process for the direct functionalization of ferrocene that exploits the high electrophilic character of gold-vinyl carbenoids catalytically generated from vinyldiazo compounds and gold complexes is reported. This process takes place with complete regioselectivity (vinilogous reactivity). The synthesis of the corresponding ruthenocene analogues has also been achieved. Preliminary studies on the reactivity of these new organometallic compounds seems to suggest that the presence of the adjacent ferrocenyl group confers a specific reactivity on the functionalized carbon chain manifested in the easy dry state aerobic allylic oxidation.More than sixty years after the discovery of ferrocene, 1 the chemistry of this organometallic compound continues to captivate chemists. This interest is based, mainly, on the huge number of applications of functionalized ferrocenes in several relevant areas including catalysis, material science and medicine. 2 Accordingly, the development of new and efficient methods for the synthesis of functionalized ferrocenes is highly desirable.In contrast to the situation found in other metallocenes, direct functionalization of the ferrocene is viable since its robust nature makes it compatible with the reaction conditions required for most common organic transformations. However, despite recent advances, 3 the number of currently available methodologies for the direct attachment of carbon chains bearing functional groups to the ferrocene remain very limited and can be classified into two general categories: a) initial Friedel-Crafts acylation followed by subsequent transformations of the resulting acylferrocene, 4 and b) initial formation of ferrocenyl lithium by treatment with alkyllithium reagents followed by coupling with a suitable carboelectrophile. 5 These classical methodologies have been successfully applied to the synthesis of many functionalized ferrocenes; however, these approaches also entail some limitations. Thus, in general, a multistep sequence is often required to install specific functionalities in remote positions. Moreover, these methodologies display a low functional group compatibility (particularly the second one, due to the high reactivity of ferrocenyl lithium).As expected, in general, Friedel-Crafts alkylation reactions of ferrocene do not represent a convenient synthetic method because mixtures of several alkylation products are formed. 6 On the other hand, the generation of electrophilic carbene species via transition-metal-catalyzed decomposition of -diazo carbonyl derivatives and their subsequent reactivity in addition and insertion reactions has become a powerful methodology in organic synthesis. 7 Surprisingly, in spite of the tremendous impact of gold catalysis in synthetic organic chemistry, 8 the use of gold complexes for the catalytic decomposition of -diazo carbonyl derivatives has been unexplored until recently. Indeed, in 2005 Nolan, Díaz-Requejo, Pérez et al reported the first gold-catalyzed decomposition of ethyl diazoacetate an...

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