tert-Butyl carbazate → tert-Butyl 2-(dihydro-2H-pyran-4(3H)-ylidene)hydrazinecarboxylate

Temperature

67.5 °C

Tetrahydro-4H-pyran-4-one (1.002 g, 10.01 mmol, CAS #29943-42-8, purchased from Fluka) was combined with tert-butyl carbazate (1.322 g, 10.00 mmol) in hexanes (10 mL). The mixture was heated in an oil bath at 65-70° C. for 75 minutes. A new precipitate began to precipitate out of solution before the carbazate completely went into solution. The mixture became very thick with the solid precipitate. Diluted with additional hexanes and heated another 15 minutes. The mixture was cooled to room temperature and concentrated in vacuo. Isopropanol was added to the residue and the mixture was stirred vigorously for 5 minutes and then diluted with ether and chilled. The solid was collected by filtration and dried in vacuo to give N′-(tetrahydro-pyran-4-ylidene)-hydrazinecarboxylic acid tert-butyl ester 1.326 g, 62%). A second crop (0.373 g, 17%) was collected from the mother liquor.

1. customto precipitate out of solution before the carbazate
2. additionDiluted with additional hexanes
3. temperatureheated another 15 minutes
4. temperatureThe mixture was cooled to room temperature
5. concentrationconcentrated in vacuo
6. additionIsopropanol was added to the residue
7. additiondiluted with ether
8. temperaturechilled
9. filtrationThe solid was collected by filtration
10. customdried in vacuo

ORD record

ord-00aa65de77f2400c997f6ded7241b20d

Source dataset

uspto-grants-2010_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07728029B2