(S)-1-N-Boc-piperazine-2-carboxylic acid methyl ester

A mixture of Compound 30C (300 mg, 1.19 mmol), l-(tert-butyl) 2-methyl (S)-piperazine-l, 2-dicarboxylate (348 mg, 2.38 mmol), and NaHCCb (200 mg, 2.38 mmol) in NMP (3 mL) was stirred at 80 C for 48 hours. The mixture was purified with Combi-flash using eluent (methanol in water (containing ammonia 0.05%), from 0% to 100% v/v) to yield Compound 30D: LC-MS (ESI) m/z: 417 [M+H]+; -NMR (CDCb, 400 MHz): d (ppm) 1.44, 1.48 (s, 9H), 2.07-2.31 (m, 2H), 2.55-2.85 (m, 5H), 3.09-3.26 (m, 1H), 3.38-3.46 (m, 1H), 3.68, 3.70 (s, 3H), 3.76-3.88 (m, 1H), 4.58, 4.75 (s, 1H), 7.29 (d, J= 8.4 Hz, 2H), 7.52 (d, J = 8.0 Hz, 2H).General procedure: A mixture of Compound 13A (605 mg, 2.46 mmol), l-(/er/-butyl) 2-methyl (f?)-piperazine-l, 2-dicarboxylate (500 mg, 2.05 mmol), and K2CO3 (424 mg, 3.07 mmol) in DMF (10 mL) was stirred at 60 C for 4 hours. The reaction mixture was diluted with water (50 mL) and extracted with ethyl acetate (50 mL x 2). The combined organic extracts were washed with brine (50 mL), dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure. The residue was purified with flash column chromatography on silica gel (ethyl acetate in petroleum ether, 10% v/v) to yield Compound 13B-1: LC-MS (ESI) m/z: 411 [M+H]+.General procedure: To a solution of Compound ID (320 mg, 1.35 mmol) in EtOH (10 mL) was added l-(tert-butoxycarbonyl)piperazine-2-carboxylic acid (311 mg, 1.35 mmol), Nal (125 mg, 0.675 mmol), and Na2CCb (574 mg, 5.42 mmol). The mixture was stirred at 78 C for 15 hours and concentrated under reduced pressure. The resulting solid was dissolved in methanol and dichloromethane (50 ml, v/v 5/100), filtered, and concentrated to furnish Compound IE: LC-MS (ESI) m/z: 431 [M+H]+.In a sealed tube, (4S, 5S)-2-methoxy-4-methyl-5-phenyl-4, 5-dihydrooxazole 10c (235 mg, 1.228 mmol) was added to a stirred mixture of (S)-l-tert-butyl 2-methyl piperazine-1, 2- dicarboxylate 118a (150 mg, 0.614 mmol) and Hunig's base (0.214 mL, 1.228 mmol) in toluene (1 mL) and the mixture was stirred at 60C overnight. The reaction was monitored by LCMS. Upon completion, the reaction mixture was concentrated in vacuo. The residue was purified by column chromatography on silica gel Teledyne ISCO REDISEP[12 g prepacked] eluting with 0- 20% EtOAc-EtOH (3 : 1)/ hexanes to give 118b.

Molecular Weight:244.29
XLogP3:0.4
Hydrogen Bond Donor Count:1
Hydrogen Bond Acceptor Count:5
Rotatable Bond Count:4
Exact Mass:244.14230712
Monoisotopic Mass:244.14230712
Topological Polar Surface Area:67.9
Heavy Atom Count:17
Complexity:298
Defined Atom Stereocenter Count:1
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes