The reductive alkylation of meldrum's acid

✍ Scribed by David M. Hrubowchak; Francis X. Smith

• Publisher: Elsevier Science
• Year: 1983
• Tongue: French
• Weight: 207 KB
• Volume: 24
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)99819-3

✦ Synopsis

Meldrum's acid can be reductively alkylated with boraneedimethylamine complex and aldehydes or ketones; boraneetrimethylamine was used with cyclohexanone. Several years ago we noted that Knoevenagel-type products derived from Meldrum's acid (2,2dimethyl-1,3-dioxane-4,6-dione ; isopropylidene malonate) are readily reduced by sodium borohy-1 dride in methanol solution. These reductions were so rapid that we felt that it might be possible to reductively alkylate Meldrum's acid in a one pot scheme. There are a few reports whit; describe the reductive alkylation of active methylene compounds under hydrogenating conditions 3 and with potassium tetracarbonylhydridoferrate. Preliminary work with sodium borohydride and aliphatic aldehydes in alcohol gave low yields; only moderate yields (30-60%) were obtained with borohydride in acetic acid media. These reactions seemed to be complicated by the concomitant reduction of the aldehyde to alcohol. Consistently good to high yields were obtained with both 4 aliphatic and aromatic aldehydes only after we used borane.dimethylamine as the reducing agent.