Yield: 2.27 g

Reaction Conditions:

Stage #1:3-tetrahydrofuroic acid with triethylamine;isobutyl chloroformate in tetrahydrofuran at 0; for 1 h;
Stage #2: with hydrazine in tetrahydrofuran at 20; for 1 h;

Steps:

6.0.6.1 (S)-Tetrahydrofuran-3-carbohydrazide and (R)-tetrahydrofuran-3-carbohydrazide, Example 6.1
(S)-Tetrahydrofuran-3-carbohydrazide and (R)-tetrahydrofuran-3-carbohydrazide, Example 6.1 (1014) To a mixture of tetrahydro-3-furanoic acid (2.0 mL, 20.9 mmol) and TEA (5.8 mL, 42 mmol) in THF (42 mL) was added dropwise isobutyl chloroformate (2.86 mL, 23.00 mmol). The resulting mixture was stirred at 0° C. for 1 h before hydrazine (0.67 mL, 23.00 mmol) was added. The resulting mixture was allowed to stir at RT for 1 h. The mixture was then concentrated, and chloroform (200 mL) and water (20 mL) were added to dissolve the residue. The organic layer was separated, and the aqueous phase was lyophilized. EtOH (50 mL×3) was used to triturate the solid 3 times. The combined EtOH solution was concentrated and dried to give tetrahydrofuran-3-carbohydrazide (2.27 g). LCMS ESI (pos) m/z=131.1 (M+H)⁺.

References:

AMGEN INC.;CHEN, Xiaoqi;CHEN, Yinhong;CHENG, Alan C.;CONNORS, Richard V.;DEBENEDETTO, Mikkel V.;DRANSFIELD, Paul John;FU, Zice;HARVEY, James S.;HEATH, Julie Anne;HEDLEY, Simon J.;HOUZE, Jonathan;JUDD, Ted C.;KHAKOO, Aarif Yusuf;KOPECKY, David John;LAI, Su-Jen;MA, Zhihua;NISHIMURA, Nobuko;OLSON, Steven H.;PATTAROPONG, Vatee;SWAMINATH, Gayathri;WANG, Xiaodong;YEH, Wen-Chen US2017/320860, 2017, A1 Location in patent:Paragraph 1013; 1014