Synthesis Of Carbamoylphosphates From Isocyanates Catalyzed By Rare-Earth-Metal Alkyl Complexes With A Silicon-Linked Diarylamido Ligand


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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)Pr(2)C6H3N)2) in good yields. The dinuclear rare-earth-metal chlorides [LRE(mu-Cl)(THF)(2)](2) (RE = Y (3), Er (4)) were synthesized by the salt metathesis reaction of H2L, (BuLi)-Bu-n, 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 CP bonds to afford various carbamoylphosphate derivatives.
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