Synthesis of Carbamoylphosphates from Isocyanates Catalyzed by Rare-Earth-Metal Alkyl Complexes with a Silicon-Linked Diarylamido Ligand

Abstract

Neutral rare-earth-metal monoalkyl complexes and anionic rare-earth-metal dialkyl complexes with a silicon-linked diarylamido ligand were synthesized and characterized, and their catalytic activities toward the additions of dialkyl phosphites to isocyanates were developed. Reactions of rare-earth-metal trialkyl complexes RE­(CH2SiMe3)3(THF)2 with a silicon-linked diarylamine ligand in n-hexane afforded the neutral rare-earth-metal monoalkyl complexes LRE­(CH2SiMe3)­(THF)2 (RE = Y (1), Er (2); L = (Me2Si)­(2,6- i Pr2C6H3N)2) in good yields. The dinuclear rare-earth-metal chlorides [LRE­(μ-Cl)­(THF)2]2 (RE = Y (3), Er (4)) were synthesized by the salt metathesis reaction of H2 L, n BuLi, and anhydrous RECl3. Treatment of the rare-earth-metal chlorides with 4 equiv of LiCH2SiMe3 in toluene generated the corresponding discrete heterobimetallic rare-earth-metal dialkyl complexes LRE­(CH2SiMe3)2(THF)­Li­(THF)4 (RE = Y (5), Er (6)). Further investigation showed that a wide variety of carbamoylphosphates were efficiently synthesized in high to excellent yields (up to 99%) via the additions of dialkyl phosphites to various alkyl- and aryl-substituted isocyanates in the presence of 0.1 mol % rare-earth-metal monoalkyl or dialkyl complexes as catalysts under solvent-free conditions at room temperature within 5 min, which provided a green and highly efficient method for the rapid construction of C–P bonds to afford various carbamoylphosphate derivatives.

Synthesis and photophysical properties of rare earth complexes bearing silanediamido ligands Me2Si(NAryl)22− (Aryl = Dipp, Mes)

“…34 More typical approaches include acid-base reactions of the protonated form of a ligand, H 2 L (proligand), with the RE alkyls, 18 or metathesis reactions of alkali metal (A) salt A 2 [R 0 2 Si(NR) 2 ] with RE halides. 17,[21][22][23][35][36][37][38] Since a salt metathesis approach is the most common, we decided to probe it with potassium and lithium salts A 2 L. To deprotonate the starting proligands, KH and BuLi were used as bases. Deprotonation of H 2 L Dipp with BuLi proceeded fast in hexane or thf/hexane solutions.…”

“…It has been recently demonstrated that such species derived from alkyl complexes [RE(L)(Alkyl)(thf) 2 ] can be used as effective catalysts of addition of isocyanates to dialkyl phosphites. 17 Similar complexes [RE(L)(N(SiMe 3 ) 2 )(thf)] (RE = Y, Nd, Sm, Eu, Yb; Aryl = Ph or 2,6-diisopropylphenyl (Dipp); R' = Me) exhibit high catalytic activity and selectivity in the cyclotrimerization of aromatic isocyanates and cyclodimerization of aliphatic isocyanates, 18 and those with macrocyclic anionic analogue [La{MeTACN(SiMe 2 )N t Bu}(CH 2 SiMe 3 )(m-CH 2 )] 2 (TACN = 1,4,7-triazacyclononane) are active in the dimerization of phenylacetylene. 19 Coordination of two ligands to the RE center would lead to anionic [RE(L) 2 ] À or ate-complexes [RE(L) 2 M] (M = alkali metals).…”

“…21 In this respect, we aimed to investigate the PL of RE complexes bearing silanediamido ligands {Me 2 Si(NDipp) 2 } 2À (L Dipp ) and {Me 2 Si(NMes) 2 } 2À (L Mes , Mes = mesityl). A series of complexes were synthesized, among them, new [{RE(L Aryl )(thf) 2 } 2 -(m-Cl) 2 ] (RE = Gd, Tb, Sm, Aryl = Dipp; RE = Y, Gd, Tb, Aryl = Mes) and a known one, [{Y(L Dipp )(thf) 2 } 2 (m-Cl) 2 ], 17 and their structures were established by single-crystal X-ray diffractometry (SXRD) and confirmed by NMR spectroscopy (for RE = Y). For lanthanide complexes, PL characteristics were determined in the solid state and solutions, in order to determine the energy of the T 1 triplet level of the ligands (for the complexes of Gd) and their potential antenna properties (for sensitization of Sm and Tb cations).…”

Hydroamination and Hydrophosphination of Isocyanates/Isothiocyanates under Catalyst‐Free Conditions

“…Our group has synthesized different types of rare‐earth metal complexes bearing a silicon‐linked diarylamido ligand and employed them in several catalytic reactions, such as cyclotrimerization or cyclodimerization of isocyanates by the rare‐earth metal amides [(Me 2 Si)(2,6‐ i Pr 2 C 6 H 3 N) 2 ]REN(SiMe 3 ) 2 (THF) (RE=Yb, Y, Sm), [15] and the additions of dialkyl phosphites to various alkyl‐ and aryl‐substituted isocyanates by the rare‐earth metal alkyl complexes [(Me 2 Si)(2,6‐ i Pr 2 C 6 H 3 N) 2 ]RE(CH 2 SiMe 3 )(THF) 2 (RE=Y, Er) [16] . Based on our previous studies on the transformation of isocyanates, we believed that the rare‐earth metal complexes can catalyze the hydroamination of isocyanates in a similar process.…”

“…All manipulations of air‐ and moisture‐sensitive materials were performed under a dry argon atmosphere using standard Schlenk techniques or in a glovebox. Rare‐earth metal complexes [(Me 2 Si)(2,6‐ i Pr 2 C 6 H 3 N) 2 ]YN(SiMe 3 ) 2 (thf), [15] and [(Me 2 Si)(2,6‐ i Pr 2 C 6 H 3 N) 2 ]Y(CH 2 SiMe 3 )(thf) 2 [16] were prepared according to the literature method. Diphenylphosphine and amines were purchased from TCI and distilled prior to use.…”