Studies on the syntheses of heterocyclic compounds. 700. Syntheses of isoquinoline alkaloids with cuprous chloride and oxygen in pyridine as an enzymic model

Homogeneous oxidative coupling catalysts. Properties of the oxidative coupling initiator obtained from the reaction of copper(I) chloride with oxygen in pyridine

“…Mechanism. The following mechanism is consistent with the kinetic dependences, rapid "CuO" + HC1 *=± "CuOHCl" K, (5) k2 "CuOHCl" -> products (6) Here, "CuOHCl" represents a protonated unit of a highly polymerized, pyridine coordinated structure,3 and step 6 is postulated to be rate determining. This mechanism predicts the observed rate law (eq 4) if A = k2Ki and B = Ku with k2 = A/B.…”

“…First, investigations of this reaction form part of a current effort to better understand the nature of the Cu1 -* Cu11 transformation in general and its role in biochemical cycles in particular.4 Second, reaction (1) in several polar, aprotic solvents (e.g., pyridine, dimethylacetamide, dimethyl sulfoxide, and hexamethylphosphoramide) provides a useful series of catalysts for the oxidative coupling of acetylenes, aromatic amines, and phenols by molecular oxygen5 and has recently been applied in interesting, biomimetic alkaloid syntheses. 6 Third, the product distribution and selective reactivity of the catalyst mixture in eq 1 bear a striking formal resemblance7 to those of copper metalloenzymes such as lacease,8 which are the subject of considerable current interest.9 Fourth, the intense, brown color of the product solutions represents an unusual spectral phenomenon in copper coordination chemistry.1 Aniline, PhNH2, can be oxidized to azobenzene in high yield in the presence of this catalyst system, eq 2.10 Our char-2PhNH2 +0,^. PhNNPh + 2H20 (2) acterization work (ref 1 and this paper) was prompted by frustrated attempts to produce high molecular weight polyazobenzenes through the corresponding oxidative coupling of p-phenylenediamine11 and its derivatives.…”

Cleavage of carbon-carbon bonds. Copper(II)-induced oxygenolysis of o-benzoquinones, catechols, and phenols. On the question of nonenzymic oxidation of aromatics and activation of molecular oxygen

“…Crystallization from acetone/chloroform gave 0.55 g of the bis adduct 8: mp 326-329 °C (70% yield); NMR ((CD3)2CO) 6.57 (d, J = 1.9 Hz, -CH=, 1 H), 4.4-3.84 (m, methine H's) + 3.97 (s, OCH3) (total 8 ), 1.03 (s, C(CH3)3, 9 H); 13C NMR ((CD3)2CO) 171.01 and 170. 20 (2 s, 4C, COOCO), 169.48 (s, C02CH3, 1 C), 154.02 (s, CC(CH3)3), 121.23 (d, -CH=), 52.82 (q, OCH3), 47.64 and 44.96 (2 d, -COCCCO-, 4 C), 33.78 (s, C(CH3)3), 28.53 (q, C(CH3)3) (the bridgehead carbon attached to the carbomethoxy group was not detected); IR (Nujol) 1860 (m) and 1790 (s, anhydride), 1740 (s, COOR), 1225, 1090, 950, 935 cm-1; mass spectrum Cl (methane/ ammonia) MH+ at mje 363.…”

“…The low yield of the cleavage products in these reactions was attributed to a possible irreversible hydrolysis of the cupric methoxide under the reaction conditions to give inactive cupric ; ¿X. (20) 30-35% oxide. Increased amounts of cupric methoxide did not lead to a higher yield of the cleavage products (Table I, entry 4).…”