Methyl 2-isocyanato-3-phenylpropenoate

Methyl 2-isocyanato-3-phenylpropenoate 365 is obtained in 68% yield by perrhenate-catalyzed decomposition of methyl 2-azido-3-phenylpropionate 364 in the presence of phosgene [257]. This reaction resulted in a higher yield compared to the same reaction employing diphosgene (instead of phosgene), which afforded the product in just 53% yield [257]. 

Typical procedure. Methyl 2-isocyanato-3-phenylpropenoate 365 [257] At 80 °C, phosgene (for a safe source, see Chapter 7) was passed into a solution of ammonium perrhenate (1 mol%) in ethyl acetate (10 mL) saturated with HCl, until the solution was saturated. A solution of 364 (4.1 g, 20.0 mmol) and hydrochinone (50 mg) in ethyl acetate (10 mL) was then added dropwise, while the mixture was cooled to 65 °C. More phosgene was then passed in, until reaction was complete (monitored by IR spectroscopy). The mixture was filtered at room temperature, the filtrate was concentrated, and the residue was distilled in vacuo to afford 2.77 g (68%) of 365. Author s remark Note Excess phosgene has to be passed into a vessel filled with ethanol to make it harmless, and thereby Hd gas is evolved (see Chapter 7). 

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See also in sourсe #XX -- [ ]

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