Methyltriphenylphosphonium Methylcarbonate, an All‐In‐One Wittig Vinylation Reagent

Abstract

The methyltriphenylphosphonium methylcarbonate salt [Ph3 PCH3 ][CH3 OCO2 ], obtained directly by quaternarization of triphenylphosphine with dimethylcarbonate, is a latent ylide that promotes Wittig vinylation of aldehydes and ketones. Alkenes are obtained simply by mixing [Ph3 PCH3 ][CH3 OCO2 ] and the carbonyl and heating in a solvent (no base, no halides, and no inorganic byproducts). Deuterium exchange experiments and the particularly short anion-cation distance measured by XRD in [Ph3 PCH3 ][CH3 OCO2 ] allowed to explain the nature and reactivity of this species. Green chemistry metrics (atom economy, mass index, environmental factor) indicate that this vinylation procedure is more efficient than comparable ones. Deuterated [Ph3 PCD3 ][CH3 OCO2 ] promoted the synthesis of deuterated olefins.

Quaternary Phosphonium Carboxylates: Structure, Dynamics and Intriguing Olefination Mechanism

“…20 The crystal packing of this ionic compound can clearly be seen in Figure 1 (A) showing phosphonium units where three Ph substituents around the phosphorus atom exhibit a typical 7 propeller-like arrangement and the bond angles enclosing the phosphorus atom range from 107.7° to 111.2°. Importantly, the distance between the acetate oxygen O1 and the benzylic proton H1 (2.147 Å, Figure 1, B) is much shorter than the earlier reported 13…”

“…9 Despite the fact that quaternary phosphonium cations (QPC) have a prominent role in the area of IP chemistry, 10 the respective tautomerisation process (Scheme 1, B) leading, via the stage of molecular complex 7, to ylides 8 has been explored relatively poorly, although experimental 11 and theoretical 12 findings pointed to the possibility of ylide formation directly from QPC salts. In this context, we note the elegant work of Perosa and coworkers 13 who demonstrated in practice the efficient vinylation with an IP reagent comprising of Ph 3 P-CH 3 + cation and methyl carbonate CH 3 OCOOanion. The feasibility of vinylation using this ionic reagent was attributed to counte-Scheme 1 A: (i) Incorporation of solvent S leads to solvent-separated 2 and ultimately free ions 5; (ii) formation of molecular complex 3; (iii) metathesis with anion Xgives new IP 4.…”

Ionic liquids as transesterification catalysts: applications for the synthesis of linear and cyclic organic carbonates

“…An example is the preparation of methyl carbonate onium salts ([Q 1 nnn ][MeOCO 2 ]; Q = N, P; n = 4, 6, 8, Ph), obtained by the methylation of trialkylphosphines or -amines with nontoxic DMC (Scheme 3, top) [34–35]. Such methyl carbonate onium salts are versatile platforms as they allow access to a number of ionic liquids via anion-metathesis reactions, which produce only CH 3 OH and CO 2 as byproducts (Scheme 3, bottom).…”

Pseudohalogen Chemistry in Ionic Liquids with Non‐innocent Cations and Anions

“…We started this project with the synthesis of various trialkylmethylammonium‐ ([R 3 MeN]: R=Et, n Pr, n Bu) [123,124] and methyltriphenylphosphonium methylcarbonates [125] . They were formed in autoclave reactions at autogenous pressure (Scheme 1), due to a modified reaction, which was first described by Werntz [126] and taken up again in later years by various working groups [127–129] …”