On the Most Powerful Chemical Traps for Bis(methoxycarbonyl)carbene (=2-Methoxy-1-(methoxycarbonyl)-2-oxoethylidene)

• Published in: Helvetica chimica acta Vol. 91; no. 3; pp. 501 - 509
• Main Authors: Shevchenko, Vladimir V., Zhegalova, Natalya G., Borzenko, Andey O., Nikolaev, Valerij A.
• Format: Journal Article
• Language: English
• Published: Zürich WILEY-VCH Verlag 01.03.2008; WILEY‐VCH Verlag
• Subjects: Carbenes; Chemical traps; Photolysis; Ylides
• ISSN: 0018-019X; 1522-2675
• DOI: 10.1002/hlca.200890054

The efficiency and validity of different chemical substrates for trapping bis(methoxycarbonyl)carbene (=2‐methoxy‐1‐(methoxycarbonyl)‐2‐oxoethylidene; 1) is dependent on the conditions of carbene generation. On conventional photolysis of dimethyldiazomalonate (=2‐diazopropanedioic acid dimethyl ester; 2) by long‐wave UV light (through a Pyrex filter, λ>290 nm), the most powerful trap for carbene 1 in the series of substrates Me2S, MeOH, cyclohexane, and pyridine is Me2S (with an efficiency ratio of ca. 6 : 4 : 2 : 1, resp.). When short‐wave decomposition of diazomalonate 2 is employed (through a quartz filter, λ>210 nm), more reliable and useful chemical traps for bis(methoxycarbonyl)carbene (1) are pyridine and cyclohexane, whose adducts with 1 are rather stable under short‐wave‐irradiation conditions. Application of alcohols for the trapping of 1 proves to be preferential when simultaneous monitoring of carbene and oxoketene formation during photolysis is necessary.