Synthesis of benzo[c]chromen-6-ones via novel cyclic aryl–Pd(II)–ester enolate intermediates

Abstract

of benzo[c]chromen-6-ones via novel cyclic aryl-Pd(II)-ester enolate Synthesis of benzo[c]chromen-6-ones via novel cyclic aryl-Pd(II)-ester enolate intermediates intermediates

1,4‐Migration of Transition Metals in Organic Synthesis

“…A 1,4‐Pd migration process (from M39 to M41 ) was proposed for these observations. The authors regarded migration might involve either Pd(II) intermediate M40 or Pd(IV) hydride M40’ (Scheme ) . However, the authors of the current review would think that a β‐hydride elimination in M40 , followed by reductive elimination in M42 could not be ruled out.…”

Transition Metal-Catalyzed Direct Arylation of Substrates with Activated sp3-Hybridized C−H Bonds and Some of Their Synthetic Equivalents with Aryl Halides and Pseudohalides

“…162 In 2007, Taylor, Ung, and Pyne found that the palladiumcatalyzed intramolecular arylation of 2-iodobenzyl 3,4-dimethoxyacetates 111 results in the formation of benzo[c-]chromen-6-ones 112 and unexpected biphenyls 113 (Scheme 48). 163 On the other hand, the palladium-catalyzed intramolecular arylation of 3,4-dimethoxybenzyl 2-iodophenylacetate 114a unexpectedly gave a separable mixture of succinate 115 (as a 1.8:1 mixture of diastereomers) and biphenyl 116, while compound 114b gave benzo [c]chromen-6-one 112b (Scheme 49). 163 Finally, in 2008, Solé and Serrano synthesized a variety of indoline 3-carboxylic acid ester derivatives 118 by intramolecular R-arylation of -(2-iodoanilino) esters 117 in refluxing THF in the presence of phenol, KOt-Bu, and catalytic quantities of Pd(PPh 3 ) 4 , but, after column chromatography, compounds 117 were partly converted to the corresponding indole derivatives 118 by air oxidation (Scheme 50).…”

“…163 On the other hand, the palladium-catalyzed intramolecular arylation of 3,4-dimethoxybenzyl 2-iodophenylacetate 114a unexpectedly gave a separable mixture of succinate 115 (as a 1.8:1 mixture of diastereomers) and biphenyl 116, while compound 114b gave benzo [c]chromen-6-one 112b (Scheme 49). 163 Finally, in 2008, Solé and Serrano synthesized a variety of indoline 3-carboxylic acid ester derivatives 118 by intramolecular R-arylation of -(2-iodoanilino) esters 117 in refluxing THF in the presence of phenol, KOt-Bu, and catalytic quantities of Pd(PPh 3 ) 4 , but, after column chromatography, compounds 117 were partly converted to the corresponding indole derivatives 118 by air oxidation (Scheme 50). 164 Interestingly, indolines 118 could also be prepared in satisfactory yields by treatment of compounds 117 with 10 mol % Pd(PPh 3 ) 4 , 3 equiv of K 3 PO 4 , and 0.3 equiv of phenol in DMF at 90°C in a sealed tube.…”

Synthetic protocols on 6$H$-benzo[$c$]chromen-6-ones: a review

“…Phenyl-2-iodobenzoates, which previously failed to cyclize under Bu 3 SnH mediated radical cyclization, 51 were adopted by Taylor and coworkers. 59 Phenyl-2-iodobenzoates (281) when treated with (Ph…”