Date Published: January 15, 2018
Publisher: John Wiley and Sons Inc.
Author(s): Joshua S. Sapsford, Daniel J. Scott, Nathan J. Allcock, Matthew J. Fuchter, Christopher J. Tighe, Andrew E. Ashley.
Despite the ever‐broadening applications of main‐group ‘frustrated Lewis pair’ (FLP) chemistry to both new and established reactions, their typical intolerance of water, especially at elevated temperatures (>100 °C), represents a key barrier to their mainstream adoption. Herein we report that FLPs based on the Lewis acid iPr3SnOTf are moisture tolerant in the presence of moderately strong nitrogenous bases, even under high temperature regimes, allowing them to operate as simple and effective catalysts for the reductive amination of organic carbonyls, including for challenging bulky amine and carbonyl substrate partners.
All reactions were prepared on the open bench unless stated otherwise. iPr3SnOTf (1) was synthesised according to literature.12 All substrates, 2,4,6‐collidine and solvents (1,2‐dichlorobenzene (DCB), 1,2‐difluorobenzene (DFB)) were purchased from commercial suppliers (Sigma Aldrich, Fluorochem, Acros Organics). Solid imines were dried under vacuum and stored under N2, while liquid imines and aldehydes were degassed, dried over 4 Å molecular sieves and stored under N2. All other compounds and solvents were used as supplied. H2 was purchased from BOC (research grade) and used without further drying or purification.