Regio- and Stereoselective Double Addition of Anionic C-Nucleophiles to Cobalt-Stabilized Acetylenedicarbaldehyde

• Published in: European journal of organic chemistry 2003-05, Vol.2003 (9), p.1641-1651
• Main Authors: Sui-Seng, Christine, Soleilhavoup, Michèle, Maurette, Luc, Tedeschi, Christine, Donnadieu, Bruno, Chauvin, Remi
• Format: Article
• Language: English
• Subjects: Alkynes; Cobalt; Diastereoselectivity; Nucleophilic addition
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.200200593

Though intrinsically unstable, Gorgues’ acetylenedicarbaldehyde is an appealing, highly functional C4 synthon, which can be stabilized by η2 complexation to a Co2(CO)6 unit. In contrast to the homologous dibenzoylacetylene complex, it can be used as a normal, doubly electrophilic, non‐conjugated γ‐dicarbonyl substrate toward alkyl‐, aryl‐, and alkynyllithium compounds or magnesium bromides; these anionic C‐nucleophiles do not predominantly attack at the metal‐carbonyl center. The 1,4‐dialkyl‐ and 1,4‐diphenylbut‐2‐yne‐1,4‐diol products are obtained with significant meso/dl diastereoselectivity (4−66% de), which can be explained by a simple model based on X‐ray diffraction data and MM calculations. The alkyl‐ and arylmagnesium bromide reactants are more selective than their lithium counterparts. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)