RESUMO
N-Arachidonoyl ethanolamide or anandamide is an endocannabinoid found in most tissues where it acts as an important signaling mediator in a number of physiological and pathophysiological processes. Consequently, intense effort has been focused on understanding all its biosynthetic and metabolic pathways. Herein we report human alcohol dehydrogenase-catalyzed sequential oxidation of anandamide to N-arachidonoyl glycine, a prototypical member of the class of long chain fatty acyl glycines, a new group of lipid mediators with a wide array of physiological effects. We also present a straightforward synthesis for a series of N-acyl glycinals including N-arachidonoyl glycinal, an intermediate in the alcohol dehydrogenase-catalyzed oxidation of anandamide.
Assuntos
Álcool Desidrogenase/metabolismo , Ácidos Araquidônicos/metabolismo , Glicina/biossíntese , Alcamidas Poli-Insaturadas/metabolismo , Catálise , Endocanabinoides , Humanos , Redes e Vias Metabólicas , OxirreduçãoRESUMO
Alpha-hydrogen abstraction and alpha-hydrogen migration reactions yield novel titanium(IV) complexes bearing terminal phosphinidene ligands. Via an alpha-H migration reaction, the phosphinidene ((tBu)nacnac)Ti=P[Trip](CH(2)(tBu) ((tBu)nacnac(-) = [Ar]NC((t)Bu)CHC((t)Bu)N[Ar], Ar = 2,6-(CHMe2)(2C6H3, Trip = 2,4,6-(i)Pr3C6H2) was prepared by the addition of the primary phosphide LiPH[Trip] to the nucleophilic alkylidene triflato complex ((tBu)nacnac)Ti=CH(t)Bu(OTf), while alpha-H abstraction was promoted by the addition of LiPH[Trip] to the dimethyl triflato precursor ((tBu)nacnac)Ti(CH)(2)(OTf) to afford ((tBu)nacnac)Ti=P[Trip](CH3). Treatment of ((tBu)nacnac)Ti=P[Trip](CH3) with B(C6F5)(3) induces methide abstraction concurrent with formation of the first titanium(IV) phosphinidene zwitterion complex ((tBu)nacnac)Ti=P[Trip]{CH3B(C6F5)(3)}. Complex ((tBu)nacnac)Ti=P[Trip]{CH3B(C6F5)(3)} [2 + 2] cycloadds readily PhCCPh to afford the phosphametallacyclobutene [((tBu)nacnac)Ti(P[Trip]PhCCPh)][CH3B(C6F5)(3)]. These titanium(IV) phosphinidene complexes possess the shortest Ti=P bonds reported, have linear phosphinidene groups, and reveal significantly upfielded solution 31P NMR spectroscopic resonances for the phosphinidene phosphorus. Solid state 31P NMR spectroscopic data also corroborate with all three complexes possessing considerably shielded chemical shifts for the linear and terminal phosphinidene functionality. In addition, high-level DFT studies on the phosphinidenes suggest the terminal phosphinidene linkage to be stabilized via a pseudo Ti[triple bond]P bond. Linearity about the Ti-P-C(ipso) linkage is highly dependent on the sterically encumbering substituents protecting the phosphinidene. Complex ((tBu)nacnac)Ti=P[Trip]{CH3B(C6F5))(3)} can catalyze the hydrophosphination of PhCCPh with H(2)PPh to produce the secondary vinylphosphine HP[Ph]PhC=CHPh. In addition, we demonstrate that this zwitterion is a powerful phospha-Staudinger reagent and can therefore act as a carboamination precatalyst of diphenylacetylene with aldimines.
Assuntos
Algoritmos , Compostos Organometálicos/química , Fosfinas/química , Fósforo/química , Titânio/química , Acetileno/análogos & derivados , Acetileno/química , Aldeídos/química , Aminação , Carbonatos/química , Catálise , Hidrogênio/química , Iminas/química , Ligantes , Espectroscopia de Ressonância Magnética , Modelos TeóricosRESUMO
A rare fluorobenzene adduct of group 4, [(nacnac)Ti=NAr(FC6H5)][B(C6F5)4] (nacnac- = [ArNC(tBu)]2CH, Ar = 2,6-iPr2C6H3), has been isolated and structurally characterized. This highly electron-deficient system engages readily in imine metathesis and catalyzes carboamination reactions involving diphenylacetylene and aldimines to afford alpha,beta-unsaturated imines as well as triaryl-substituted quinolines. The latter product results from cyclization of the corresponding electron-rich alpha,beta-unsaturated imine.
RESUMO
Sulfenyl thiocyanate (RSSCN) derivatives of penicillamine (PENSCN) and glutathione (GSSCN) have been synthesized in situ at pH = 0 from equilibrium mixtures that consists of hypothiocyanous acid (HOSCN), thiocyanogen ((SCN)2), and trithiocyanate ((SCN)3-). The electrophilic thiocyanating agent N-thiocyanatosuccinimide (NTS) also reacts with PEN and GSH to yield the corresponding RSSCN derivatives. PENSCN and GSSCN were characterized by NMR, ES-MS, and IR spectroscopy. While stable at pH = 0, at higher pH the RSSCN derivatives decompose to give products that are consistent with hydrolysis and formation of reactive sulfenic acids.