Cyclometalated iridium complexes are shown to be highly efficient and chemoselectivecatalysts for the transferhydrogenation of a wide range of carbonyl groups with formic acid in water. Examples include α‐substituted ketones (α‐ether, α‐halo, α‐hydroxy, α‐amino, α‐nitrile or α‐ester), α‐keto esters, β‐keto esters and α,β‐unsaturated aldehydes. The reduction was carried out at substrate/catalyst ratios of
“High-surface alkali metals” can be conveniently prepared via deposition of corresponding metals on various supports such as sodium chloride, polyethylene, polypropylene and cross-linked polystyrene from their solutions in liquid ammonia. Alkali metals deposited on polymeric supports can be stored in form of stable suspensions in inert solvents and used for the acyloin and Dieckmann condensations and
concentration of ammonia in the reaction medium. Zinc (A) prepared in liquid ammonia (Method A) was much less active then zinc (B) prepared in THF containing 10–20 volume % of liquid ammonia (Method B). The X-ray powder diffractometry data suggested that zinc (B) was less crystalline then zinc (A). The Reformatsky and Barbier type reactions of carbonyl compounds with α-bromoesters, allylic and propargylic
Bu4N+-Controlled Addition and Olefination with Ethyl 2-(Trimethylsilyl)acetate via Silicon Activation
作者:Donal O’Shea、Manas Das、Atul Manvar、Ian Fox、Dilwyn Roberts
DOI:10.1055/s-0036-1588805
日期:2017.11
β-hydroxy esters, whereas employing catalytic Bu4NOTMS gave α,β-unsaturatedesters. The established reaction conditions were applicable to a diverse range of aromatic, heteroaromatic, aliphatic aldehydes and ketones. Reactions were achieved at room temperature without taking any of the specialized precautions that are in place for other organometallics. A stepwise olefination pathway via silylated