Phosphanalkylene, 52. Umsetzung von [1‐(Trimethylsilyl)alkyliden]triphenylphosphoranen mit Kohlendioxid und Folgereaktionen

Abstract

Phosphane Alkylenes, 52[1]. – Reactions of [1‐(Trimethylsilyl)alkylidene]triphenylphosphoranes with Carbon Dioxide 2‐(Triphenylphosphoranylidene) carboxylic acid esters 6 have been synthesized from 1‐(trimethylsilylalkylidene)phosphoranes 4 and carbon dioxide. The reactions of the ylides 6 with aldehydes 9 lead to α,β‐unsaturated silyl esters 10 in good yields and with high (E) stereoselectivity. Thermolysis of 6d affords (oxovinylidene)triphenylphosphorane (7).

CO2 Adducts of Phosphorus Ylides: Highly Active Organocatalysts for Carbon Dioxide Transformation

“…This is ascribed to the intermolecular migration of TMS to an oxygen atom in a CO 2 molecule to generate new P-ylides functionalized by a silyl ester group, and these easily react with additional aldehydes to afford α,βunsaturated silyl esters (Scheme 1c). 16 However, there has been no report of a P-ylide or its CO 2 adduct as an organocatalyst for CO 2 activation and chemical transformation. In the present contribution, various P-ylide−CO 2 adducts were synthesized and carefully characterized, especially with a focus on the difference in thermal stability in comparison with that of the previously studied NHC−CO 2 and NHO−CO 2 adducts.…”

“…P-ylide–CO 2 adducts containing a trimethylsilyl (TMS) group on the ylidic carbon atom were chemically unstable. This is ascribed to the intermolecular migration of TMS to an oxygen atom in a CO 2 molecule to generate new P-ylides functionalized by a silyl ester group, and these easily react with additional aldehydes to afford α,β-unsaturated silyl esters (Scheme c) . However, there has been no report of a P-ylide or its CO 2 adduct as an organocatalyst for CO 2 activation and chemical transformation.…”

One-pot formation of 2,4-di- or 2,4,6-tri-olefinic monocarboxylic acids by straight chain C4-extension

“…We are here concerned with the direct formation of α,β-unsaturated carboxylic acids by carbon chain extension of aldehydes. Previous reactions of this kind are limited to C2-extension: Peterson olefination [1] , Wittig-Horner type reaction [ 2 , 3 ], extension by (trimethylsilyl)ketene [4] or its acetal [5] and Knoevenagel extension with malonic acid [ 6 , 7 ]. We now report a reaction which extends the carbon skeleton by a straight chain unit of four carbon atoms, thereby simultaneously introducing two conjugated olefinic bonds and a free carboxylic acid group.…”

Transition-Metal-Free Reductive Deoxygenative Olefination with CO2

“…In 1966, Matthews et al first reported that nucleophilic addition of phosphorus ylides to CO 2 afforded phosphonium–CO 2 inner salts easily (Scheme b) . This kind of salt could be transformed into other products, such as ketene, carboxylic acids, etc . Notably, Zhou, Lu, and co-workers recently used it as a stable catalyst for efficient CO 2 transformation .…”