Does Nitroarylation of Phenylacetonitrile Proceed as a Phase-Transfer Catalyzed Process?
摘要:
The phase-transfer catalyzed reaction of phenylacetonitrile with 4-chloro-3-(trifluoromethyl)nitrobenzene produces 5-chloro-7-phenyl-4-(trifluoromethyl)benzisoxazole (5) not the nitroarylation product 3a as was reported by Durantini et al. (Durantini, E. N.; Chiacchiera, S. M.; Silber, J. J. J. Org. Chem. 1993, 58, 7115). The catalytic nitroarylation does not occur because the product 3a immediately forms a lipophilic carbanion which inhibits the catalytic process. The nitroarylation occurs under ion-pair extraction conditions when a stoichiometric amount of tetrabutylammonium bromide is used, whereas 2-phenylalkanenitriles are efficiently PTC nitroarylated. 4-Chloro-3-(trifluoromethyl)- and 2-chloro-5-(trifluoromethyl)nitrobenzenes enter vicarious nucleophilic substitution reactions with carbanions of chloromethyl p-tolyl sulfone. These results and formation of 5 show that carbanions add to these nitroarenes initially in positions occupied with hydrogen.
Catalytic hydrogenation of 2-nitrophenylacetonitriles bearing an aromatic substituent α to the nitrile group, using Pd/C and (Ph3P)4Pd, affords unstable N-hydroxy-2-amino-3-arylindoles which, after autoxidation, yields 2-amino-3-aryl-3H-indol-3-ol 1-oxides.
Does Nitroarylation of Phenylacetonitrile Proceed as a Phase-Transfer Catalyzed Process?
作者:Mieczyslaw Makosza、Alexander A. Tomashewskij
DOI:10.1021/jo00122a019
日期:1995.9
The phase-transfer catalyzed reaction of phenylacetonitrile with 4-chloro-3-(trifluoromethyl)nitrobenzene produces 5-chloro-7-phenyl-4-(trifluoromethyl)benzisoxazole (5) not the nitroarylation product 3a as was reported by Durantini et al. (Durantini, E. N.; Chiacchiera, S. M.; Silber, J. J. J. Org. Chem. 1993, 58, 7115). The catalytic nitroarylation does not occur because the product 3a immediately forms a lipophilic carbanion which inhibits the catalytic process. The nitroarylation occurs under ion-pair extraction conditions when a stoichiometric amount of tetrabutylammonium bromide is used, whereas 2-phenylalkanenitriles are efficiently PTC nitroarylated. 4-Chloro-3-(trifluoromethyl)- and 2-chloro-5-(trifluoromethyl)nitrobenzenes enter vicarious nucleophilic substitution reactions with carbanions of chloromethyl p-tolyl sulfone. These results and formation of 5 show that carbanions add to these nitroarenes initially in positions occupied with hydrogen.
Cation-Controlled Enantioselective and Diastereoselective Synthesis of Indolines: An Autoinductive Phase-Transfer Initiated 5-<i>endo</i>-<i>trig</i> Process
作者:Krishna Sharma、Jamie R. Wolstenhulme、Phillip P. Painter、David Yeo、Francisca Grande-Carmona、Craig P. Johnston、Dean J. Tantillo、Martin D. Smith
DOI:10.1021/jacs.5b08834
日期:2015.10.21
A catalytic enantioselective approach to the synthesis of indolines bearing two asymmetriccenters, one of which is all-carbon and quaternary, is described. This reaction proceeds with high levels of diastereoselectivity (>20:1) and high levels of enantioselectivity (up to 99.5:0.5 er) in the presence of CsOH·H2O and a quinine-derived ammonium salt. The reaction most likely proceeds via a delocalized