strategy activated the C-Br bonds of α-bromo-alkylcarboxylic esters to provide carbon-centered radicals under the catalysis of Ir(iii) photocatalyst and coupled with indole derivatives. This methodology displayed wide functional group tolerance and excellent regioselectivity, and was applied to the late-stage functionalization and preparation of indole-containing hybrids.
Herbicidal 2-(phenoxy or phenylthio)-2-(,3,5-triazinyloxy) alkanoic acids
申请人:DowElanco
公开号:US05232896A1
公开(公告)日:1993-08-03
2-(Phenoxy or phenylthio)-2-(pyrimidinyloxy or 1,3,5-triazinyloxy)alkanoic acid compounds, such as ethyl 2-(2-fluorophenoxy)-2-(4,6-dimethylpyrimidin-2-yloxy)-acetate, were prepared by the reaction of a phenol or thiophenol compound with a 2-chloro-2-(pyrimidinyloxy or 1,3,5-triazinyloxy)alkanoate ester compound or by the reaction of a pyrimidinol or 1,3,5-triazinol with a 2-bromo-2-(phenoxy or phenylthio)alkanoate ester. These compounds, and, especially, agriculturally acceptable salts, esters, and amides of these compounds, were found to have herbicidal utility.
Eighteen phosphorus-based alkerrylation reagents 1a-6c were synthesized and condensed with n-butyraldehyde 7a and benzaldehyde 7f. They were condensed with the aldehydes 7b-e,g-n to produce 2-methoxy-2-alkenoates 8a-n and 2-phenoxy-2-alkenoates 9a-n. A discussion on different selectivities for the alkerrylation reagents under different experimental conditions (base, soh em, temperature), the influence of the aldehydes on the geometrical outcome (electron rich or poor substituents steric hindrance) and the selection of the most E-and Z-selective reaction conditions for each class of aldehydes are reported Namely, triphenyl phosphonium salt la at RT in THF with DBU was better for Z-selectivity while trifluoroethylphosphonates 5b, 6b and 6c at -78 degrees in THF with KN(SiMe3)(2) were better for E-selectivity. (C) 1997 Elsevier Science Ltd.
Synthetic applications of heteroatom-directed photoarylation. Benzo[b]furan ring construction
作者:Arthur G. Schultz、James J. Napier、Ramanathan Ravichandran