N‑Methoxy‑N‑methylcyanoformamide, a Highly Reactive Reagent for the Formation of β‑Keto Weinreb Amides and Unsymmetrical Ketones

A rapid and straightforward synthesis of the new and highly reactive reagent N-methoxy-N-methylcyanoformamide from trimethylsilyl cyanide and N-methoxy-N-methylcarbamoylimidazole, is reported. This reagent enables the one-pot preparation of β-carbonyl Weinreb amides from lithium enolates, one-carbon homologated Weinreb amides, and unsymmetrical ketones in one-pot procedures from various organometallic species.