On the Alkylation of Ph₃PCHP(O)Ph₂: Formation and Crystal Structures of Neutral and Cationic Addition Compounds

Abstract

Ylide Ph3PCHP(O)Ph2 (1) is the hydrolysis product of carbone C(PPh3)2 and reacts with MeI to produce the corresponding salt [Ph3PCH(Me)P(O)Ph2]I (2). Deprotonation of the cation of 2 with K[N(SiMe3)2] in methyl cyclohexane or toluene gives neutral ylide Ph3PCMeP(O)Ph2 (7). Addition of AlBr3 at the oxygen atom of 7 involves simultaneous uptake of a proton along with formation of [Ph3PCH(Me)P(OAlBr3)Ph2][AlBr4] (9). Small amounts of resultant proton bridged [H{Ph2(O)PCH(Me)PPh3}2][I3]3 (10) were isolated during attempts to silylate 2 with trimethylsilytriflate; the main product was found to be [Ph3PCH(Me)P(O)Ph2](O3SCF3) (8). In the course of our studies several by‐products with cation [Ph3PCH2P(O)Ph2]+ (4 to 6) were obtained. All compounds were characterized by multiple NMR and X‐ray analyses.

Syntheses and Crystal Structures of Copper and Silver Complexes with the Ylide Ph3PCHP(O)PPh2 as Ligand

“…In recent papers we reported on addition compounds of 2 with Lewis acids A such as group 13 compounds BX 3 (X = F, I), AlBr 3 , and SnCl 2 , which exclusively coordinate at the oxygen atom to give neutral compounds of the type 2(O)ǞA; [3] an O coordination was also found with the electron deficient W(CO) 5 fragment. [4] In a preceding paper, the results of the alkylation of 2 were presented.…”

“…Alkylation with MeI or protonation proceeds at the ylidic carbon atom with quantitative formation of the salts [Ph 3 PCHMeP(O)Ph 2 ]I or [Ph 3 PCH 2 P(O)Ph 2 ]I, respectively, abbreviated as (2(C)ǞMe) + and (2(C)ǞH) + . [5] A second row of cationic compounds was also formed, in which additionally to O coordination the ylidic carbon atom is protonated leading to sp 3 hybridization and formation of compounds of the type (Hǟ(C)2(O)ǞA) + ; [6] among them an alkylated product (Meǟ(C)2(O)ǞA) + with A = www.zaac.wiley-vch.de ARTICLE AlBr 3 could also be isolated. [5] The carbon atoms in 2(O)ǞA addition compounds show sp 2 hybridization as in the starting ylide 2.…”

“…[5] A second row of cationic compounds was also formed, in which additionally to O coordination the ylidic carbon atom is protonated leading to sp 3 hybridization and formation of compounds of the type (Hǟ(C)2(O)ǞA) + ; [6] among them an alkylated product (Meǟ(C)2(O)ǞA) + with A = www.zaac.wiley-vch.de ARTICLE AlBr 3 could also be isolated. [5] The carbon atoms in 2(O)ǞA addition compounds show sp 2 hybridization as in the starting ylide 2. H + addition as well as alkylation of 2 adopts a distorted tetrahedral environment at the carbon atom.…”

Phosphonium salts and P-ylides

“…267 A very interesting study by Petz and Neumüller was focused on the alkylation of Ph 3 PCHP(O)Ph 2 . 268 The reaction proceeded exclusively at the carbon atom, but uptake of a proton from various solvents was also observed in the presence of a Lewis acid. Solomon, Wright and co-workers attempted the synthesis of the ylide dianion [2,4,6-Me 3 C 6 H 2 P-(CHR) 3 ] 2À (where R ¼ H or Me).…”

Phosphonium salts and P-ylides

“…267 A very interesting study by Petz and Neumüller was focused on the alkylation of Ph 3 PCHP(O)Ph 2 . 268 The reaction proceeded exclusively at the carbon atom, but uptake of a proton from various solvents was also observed in the presence of a Lewis acid. Solomon, Wright and co-workers attempted the synthesis of the ylide dianion [2,4,6-Me 3 C 6 H 2 P-(CHR) 3 ] 2À (where R ¼ H or Me).…”