Synthesis of carbonyl compounds using organomanganese pentacarbonyl complexes.

✍ Scribed by Philip DeShong; Greg A Slough; Arnold L Rheingold

• Publisher: Elsevier Science
• Year: 1987
• Tongue: French
• Weight: 248 KB
• Volume: 28
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)96087-8

✦ Synopsis

Sequential insertion of carbon monoxide and either strained or electron-deficient alkenes into alkylmanganese pentacatinyl complexes at pressures of 6 kbar provides manganacycles in a regioselective and stereoselective fashion. The manganacycles can be transformed into carbonyl compounds under photolytic conditions.

The insertion of transition metal-carbon bonds into carbon-carbon or carbon-oxygen multiple bonds is a key reaction in many processes involving heterogeneous and homogeneous transition metal catalysts.2W4 The prototypic example of this process is the migratory insertion of alkylmanganese pentacarbonyl complexes which has been extensively studied.5sg For example, Booth and coworkers have demonstrated that terminal alkynes and strained alkenes reacted with activated manganese complexes such as methylmanganese pentacarbonyl (1, Rl=Me) at atmospheric pressure to furnish complex 2 (R'=Me) in modest yield resulting from a sequential insertion of carbon monoxide and the alkyne moiety (Scheme).8 However, these same authors also reported that the sequential insertion process was not a general one since if either the alkylmanganese or alkene component was deactivated the process failed to occur.

In this Communication, we report that alkylmanganese pentacarbonyl complexes (1) react regio-and stereoselectively with either strained or electron-deficient alkenes at pressures of 6 kbar to produce manganacycle 3 in good yield. The resulting manganese complex is a versatile intermediate for the synthesis of carbonyl compounds as indicated in the Scheme. This approach to the synthesis of highly functionalized ketones occurs with formation of two new carbon-carbon bonds and the introduction of one molecule of carbon monoxide. Scheme