An exceptionally mild method for the preparation of isatin derivatives has been developed using a sulfur ylide mediated carbonyl homologation sequence starting from anthranilic acid precursors. This method proceeds at ambient temperature via a sulfur ylide intermediate without the need for protection of the amine or chromatographic isolation of the intermediate ylide. Gentle oxidation of the sulfur ylides provides isatin derivatives with N-H, N-alkyl, N-aryl substitution, electron-rich and electron-poor aromatic rings, and heterocyclic aromatic systems. We anticipate that this method will greatly expand the accessibility of complex isatin derivatives.

Noninvasive measurement of oxidative markers in clinical samples has the potential to rapidly provide information for disease management, but is limited by the need for expensive analytical instrumentation that precludes home monitoring or point-of-care applications. We have developed a simple to use diagnostic platform for airway hydrogen peroxide (H2O2) that combines optimized reaction-based chemiluminescent designs with an inexpensive home-built darkbox and readily available smartphone cameras. Specialized photography software applications and analysis of pixel intensity enables quantification of sample concentrations. Using this platform, sample H2O2 concentrations as low as 264 nM can be detected. The platform has been used to measure H2O2 in the exhaled breath condensates of human subjects, showing good agreement with the standard Amplex Red assay.

Ylide Mediated Carbonyl Homologations for the Preparation of Isatin Derivatives. -The reaction proceeds via the in situ generated sulfur ylide intermediates. The N-protection and isolation of the intermediates are not required. -(LOLLAR, C. T.; KRENEK, K. M.; BRUEMMER, K. J.; LIPPERT*, A. R.; Org. Biomol. Chem. 12 (2014) 3, 406-409, http://dx.