Alkyne dicobalt complexes in carbohydrates: Synthetic applications

Abstract

The complexation of alkynes to form dicobalt hexacarbonyl derivatives facilitates the formation, under acid catalysis, of highly stabilized propargylic cations whose reaction with nucleophiles to form propargylic compounds, currently known as the Nicholas reaction, has found ample use in organic synthesis. This transformation has shown to be particularly useful when applied to carbohydrate derivatives. In this chapter, we provide a brief overview on this subject pioneered by early contributions from Isobe's research group. Thus, carbohydrate-derived dicobalt hexacarbonyl complexes have been used in the epimerization of C-alkynyl glycosides, pyranose ring-opening nucleophile trapping reactions, pyranose ring-opening ring-recyclization leading to medium-sized oxacycles, glycosylation strategies, C-glycosylation and pyranose to carbocycle transformations among others. Finally, contributions from our research group focusing on the synthetic applications of Ferrier-Nicholas cations are also presented.

Synthesis and Determination of Anticancer Activity of Dicobalt Hexacarbonyl 2′-Deoxy-5-alkynylfuropyrimidines

“…Cobalt carbonyl alkyne complexes have established their presence among the biologically active organometallic components and are attracting substantial interest as antiproliferative agents and CO-releasing molecules (CORMs). − A representative example is a peptide conjugate ( 1 , Figure ) that shows significant toxicity against tumor cell lines. − Recently, dicobalt hexacarbonyl derivatives of methyl-substituted acetylsalicylic acid ( 2 , Figure ) have been determined as cytotoxic cyclooxygenase (COX) inhibitors and showed reduced effects at the isolated COX-1 and high cytotoxicity toward the COX-positive HT-29 colon carcinoma cells. Interference of the arachidonic acid cascade through COX-2 inhibition as part of the mode of action has been suggested .…”