Boc-D-His(1-Me)-OH

The reaction of N-heterocyclic carbene (NHC) Group 11 metal complexes, [(NHC)M-X] (X = chloride, acetate), with the new azide-modified arylthiol 1-HSCH2-2,5-Me2-4-N3CH2-C6H2, 1 (for M = Au; X = Cl), or 1-Me3SiSCH2-2,5-Me2-4-N3CH2-C6H2, 2 (for M = Cu, X = Cl; M = Ag, X = OAc), affords the "clickable" NHC-metal thiolates [( iPr2-bimy)Au-(1-SCH2-2,5-Me2-4-N3CH2-C6H2)], 5; [(IPr)Au-(1-SCH2-2,5-Me2-4-N3CH2-C6H2)], 6; [(IPr)Ag-(1-SCH2-2,5-Me2-4-N3CH2-C6H2)], 7; and [(IPr)Cu-(1-SCH2-2,5-Me2-4-N3CH2-C6H2)], 8 ( iPr2-bimy = 1,3-di-isopropylbenzimidazol-2-ylidene, IPr = 1,3-bis(2,6-di-iso-propylphenyl)imidazol-2-ylidene). Single-crystal X-ray analysis of all metal complexes show that they are two-coordinate, nearly linear, with a terminally bonded thiolate ligand possessing an accessible azide (-N3) moiety. The strain-promoted alkyne-azide cycloaddition (SPAAC) reaction of complex 6 with bicyclo[6.1.0]non-4-yn-9-ylmethanol (BCN-OH) and dibenzocyclooctyne-amine (DBCO-NH2) illustrated the reactivity of the azide moiety toward strain-promoted cycloaddition. The rate of the SPAAC reaction between complex 6 and BCN-OH was determined via 1H NMR spectroscopy under second order conditions, and was compared to that of BCN-OH with PhCH2N3.

Six novel organotin phosphonate complexes, [(Me3Sn)4(HL1)4]n1, [(Me3Sn)2(HL2)2]n2, [(Me3Sn)2L3(H2O)]n3, [(Ph3Sn)(HL1)]64, [(Ph3Sn)2L2]n5 and [(Ph3Sn)2L3]66, derived from phosphonic acid ligands [NaHL1 = 1-C10H7OPO2(OH)Na, H2L2 = 1-C10H7PO(OH)2, H2L3 = 2-C10H7PO(OH)2], have been synthesized and characterized by elemental analysis, FT-IR, NMR (1H, 13C, 31P and 119Sn) spectroscopy and X-ray crystallography. The structural analysis reveals that complexes 1 and 5 display 1D infinite zig-zag chain structures, and complex 2 shows 1D right-handed helical chain structure, while complex 3 displays 1D left-handed helical chain structure. Complexes 4 and 6 are 24-membered macrocyclic rings interconnected by P, O and Sn atoms. Additionally, the molecules of complexes 1 and 3 are further linked through intermolecular π···π and O-H···O interaction into supramolecular structures, respectively. Furthermore, we preliminarily estimated in vitro cytostatic activity of complexes 1-6 against the human cervix tumor cells (HeLa), human hepatocellular carcinoma cells (HepG-2) and human normal breast cells (HBL-100). Importantly, the anti-proliferative properties and possible pathway of complex 6 are investigated, and the results demonstrate that complex 6 could induce apoptotic cell death via an overload of intracellular reactive oxygen species (ROS) levels and the dysfunctional depolarization of mitochondrial membranes.

Mixed-ligand diorganotin esters, [R 2Sn(OP(O)(OH)Ph)(OS(O) 2R (1))] n [R = n-Bu, R (1) = Me ( 1), n-Pr ( 2); R = Et, R (1) = Me ( 3)], have been synthesized by reacting the tin precursors, R 2Sn(OR (1))OS(O) 2R with an equimolar amount of phenylphosphonic acid under mild conditions (room temperature, 6-8 h, CH 2Cl 2). These have been characterized by IR, multinuclear ( (1)H, (13)C{ (1)H}, (31)P, and (119)Sn) NMR, and single crystal X-ray diffraction studies. The asymmetric unit of 1 is comprised of a tetramer with four crystallographically unique tin atoms. The structure reveals a central eight-membered (Sn-O-S-O) 2 cyclic ring with two exocyclic tin atoms, which results from micro 3-binding of the two methanesulfonate groups. The remaining two sulfonates are monodentate and contribute in O...HO(P) hydrogen bonding. The molecular structure is extended into a 3D coordination polymer with the aid of hydrogenphenylphosphonate group on each tin atom, acting in a micro 2-O 2P mode and forms a series of eight-membered (Sn-O-P-O) 2 rings in the structural framework. 2 and 3 are isostructural and represent linear 1D coordination polymers via micro 2-binding mode of both alkanesulfonate and hydrogenphenylphosphonate groups.