O-Carbonylation

Benzisothiazoles are formed by the action of ammonia or amines on benzenesulfenyl halides bearing an o-carbonyl function (72AHC 14)43, 80MI41700). Analogous diphenyl disulfides behave similarly (77SST(4)339). Sulfinyl chlorides or phenylsulfoxides produce... 

Casares, J.A., Espinet, P., Hernando, R., Iturbe, G., Villafane, F., Ellis, D.D. and Orpen, A.G. (1997) Poly(2-pyridyl) phosphines, PPynPh3 (n = 2, 3), and Their P-Substituted Derivatives as Tripodal Ligands in Molybdenum(O) Carbonyl Complexes. Inorganic Chemistry, 36(1), 44-49. 

Apart from glycosyl acetate and benzoate donors, more elaborate O-carbonyl derivatives offer potential for distinct modes of anomeric leaving group activation. Many of these donors (Scheme 3.21) involve activation of an anomeric O-carbonyl derivative 134 at a remote functional group (Y). The adivated remote functionality, in turn,... 

Glycosyl esters with remote functionality constitute a relatively new class of O-carbonyl glycosyl donors, which fulfill the prospect of mild and chemoselective activation protocols (Scheme 3.22). For example, Kobayashi and coworkers have developed a 2-pyridine carboxylate glycosyl donor 134 (Y = 2-pyridyl), which is activated by the coordination of metal Lewis acid (El+) to the Lewis basic pyridine nitrogen atom and ester carbonyl oxygen atom [324]. In the event, 2-pyridyl (carbonyl) donor 134 and the monosaccharide acceptor were treated with copper(II) triflate (2.2 equiv) in diethyl ether at —50 °C, providing the disaccharide 136 in 70% (a P,... 

The high yields, stereochemical control and mild reaction conditions make this class of O-carbonyl donors an attractive option. 

Calculations (Hacker and Kasai 1993) in the framework of extended Hueckel theory found the LUMO of o-diazobenzoquinone to be mainly (up to 60%) localized at the N—N sector. The electronegativity of the o-carbonyl oxygen enhances the acceptor properties of the diazo group. Charge-spin separation is an understandable consequence of the situation. 

Ring Closure of o-Carbonylated Phenols or Phenol Ethers... 

The cyclization of o-carbonylated a-aryloxyalkanoic acids or esters (Rossings method) has yielded numerous benzo[6]furans (see Section 3.12.5). The condensation of o-hydroxylated... 

The nickel(II) complexes with the ligand diars (XVIII) were first reported by Nyholm. The NiX2(diars)2 complexes were prepared from the reactants in hot ethanol.1318 The 1 1 complexes were originally prepared by oxidation of the nickel(O) carbonyl complex with gaseous hydrogen halides under anaerobic conditions (equation 161).1283 Other complexes with diars were subsequently prepared according to equations (162)-(164).1319-1321... 

The oxidation of a nickel(O) carbonyl compound with halogens was employed by Chatt and Hart to prepare nickel(II) complexes with the diphosphine ligand (XVII R = Et equation 165) 1311 2 1 complexes were subsequently prepared by the direct synthesis of the reactants in acetone.1287... 

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