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.

Three β-diketiminato proligands incorporating a thiophene or tetrahydrofuran heterocyclic group, H2 L1 , H2 L2 , and HL3 (MeC­(NDipp)­CHC­(Me)­N­(CH2)n-2-(HCG), HCG = C4H2S, n = 2, L1 ; n = 1, L2 ; HCG = C4H7O, n = 1, L3 ; Dipp = 2,6- i Pr2C6H3), have been developed. Unusual N,N,C tridentate β-diketiminato rare-earth metal monoalkyl complexes L1 RE­(CH2SiMe3)­(thf) (RE = Y (1a), Er (1b), Yb (1c), Lu (1d), thf = tetrahydrofuran) and L2 Yb­(CH2SiMe3)­(thf) (2c) were achieved unexpectedly by the reactions of RE­(CH2SiMe3)3(thf)2 with H2 L1 and H2 L2 , respectively. In this process, the C–H bond activation of the thiophene ring occurred. In sharp contrast, the treatment of RE­(CH2SiMe3)3(thf)2 with a tetrahydrofuran-functionalized β-diketiminato proligand HL3 , under the same conditions, gave five-coordinate N,N,O tridentate β-diketiminato rare-earth metal dialkyl complexes L3 RE­(CH2SiMe3)2 (RE = Y (3a), Er (3b), and Yb (3c)). In addition, their unique catalytic performances have been described. The monoalkyl complexes exhibited high efficiency toward the dimerization of various aldehydes, providing a wide range of carboxylic esters in good to high yields under mild conditions. The dialkyl complexes could promote the head-to-head dimerization of terminal alkynes to afford conjugated 1,4-disubstituted enynes with excellent regio- and stereoselectivity (up to 100% Z-selectivity). More importantly, a rare type of rare-earth metal complexes [{L 3RE­(μ-CCPh)}2(μ-η2:η2-PhCCCCPh)] (RE = Y (6a), Er (6b)) containing two bridging alkynyl groups and a Z-butatrienediyl fragment were isolated and characterized by the reaction of N,N,O tridentate rare-earth metal dialkyls with phenylacetylene, which is unarguably responsible for the outcome of Z-configured enynes during alkyne dimerization.

Novel N,N,N-tridentate β-diketiminato rare-earth-metal dialkyl complexes LRE­(CH2SiMe3)2 [RE = Y (1a), Gd (1b), Yb (1c), Lu (1d); L = MeC­(NDipp)­CHC­(Me)­N­(CH2)2NC4H8, where Dipp = 2,6- i Pr2C6H3] have been conveniently synthesized by one step from reactions of the rare-earth-metal trialkyl complexes RE­(CH2SiMe3)3(THF)2 (THF = tetrahydrofuran) with a pyrrolidine-functionalized β-diketiminate HL, and their catalytic behaviors toward hydroalkoxylation and tandem hydroalkoxylation/cyclohydroamination of isocyanates have been described. These rare-earth-metal catalysts exhibited high efficiency in the hydroalkoxylation of isocyanates, providing a variety of N-alkyl and N-aryl carbamate derivatives under mild reaction conditions with a rather low catalyst loading (0.04 mol %). More significantly, they can promote a tandem hydroalkoxylation/cyclohydroamination reaction between terminal and internal propargylic alcohols with substituted arylisocyanates, leading to the efficient synthesis of methylene and (Z)-selective arylidene oxazolidinones in good-to-high yields via consecutive C–O and C–N bond formation. The stoichiometric reaction of 1a with p-tolylisocyanate generated an unusual dinuclear yttrium complex, {[η2-(4-MePhNCO)­(CH2SiMe3)]­Y­[μ-η2:η1:η1-(4-MePhNCO)­CC­(Me)­(NDipp)­C­(Me)­N­(CH2)2NC4H8]}2 (7a), with two different amidate units, which underwent an sp2 C–H bond activation of the β-diketiminato backbone, followed by the insertion of isocyanate.

Billions of apoptotic cells are removed daily in a human adult by professional phagocytes (e.g. macrophages) and neighboring nonprofessional phagocytes (e.g. stromal cells). Despite being a type of professional phagocyte, neutrophils are thought to be excluded from apoptotic sites to avoid tissue inflammation. Here we report a fundamental and unexpected role of neutrophils as the predominant phagocyte responsible for the clearance of apoptotic hepatic cells in the steady state. In contrast to the engulfment of dead cells by macrophages, neutrophils burrowed directly into apoptotic hepatocytes, a process we term perforocytosis, and ingested the effete cells from the inside. The depletion of neutrophils caused defective removal of apoptotic bodies, induced tissue injury in the mouse liver and led to the generation of autoantibodies. Human autoimmune liver disease showed similar defects in the neutrophil-mediated clearance of apoptotic hepatic cells. Hence, neutrophils possess a specialized immunologically silent mechanism for the clearance of apoptotic hepatocytes through perforocytosis, and defects in this key housekeeping function of neutrophils contribute to the genesis of autoimmune liver disease.

Billions of apoptotic cells are removed daily in a human adult by professional phagocytes (e.g. macrophages) and neighboring nonprofessional phagocytes (e.g. stromal cells). Despite being a type of professional phagocyte, neutrophils are thought to be excluded from apoptotic sites to avoid tissue inflammation. Here we report a fundamental and unexpected role of neutrophils as the predominant phagocyte responsible for the clearance of apoptotic hepatic cells in the steady state. In contrast to the engulfment of dead cells by macrophages, neutrophils burrowed directly into apoptotic hepatocytes, a process we termperforocytosis, and ingested the effete cells from the inside. The depletion of neutrophils caused defective removal of apoptotic bodies, induced tissue injury in the mouse liver and led to the generation of autoantibodies. Human autoimmune liver disease showed similar defects in the neutrophil-mediated clearance of apoptotic hepatic cells. Hence, neutrophils possess a specialized immunologically silent mechanism for the clearance of apoptotic hepatocytes through perforocytosis, and defects in this key housekeeping function of neutrophils contribute to the genesis of autoimmune liver disease.