ChemicalBook CAS DataBase List Methyl (S) - 4 - Methylene - 1 - (benzyloxycarbonyl)pyrrolidine carboxylate

Methyl (S) - 4 - Methylene - 1 - (benzyloxycarbonyl)pyrrolidine carboxylate synthesis

8synthesis methods

Product Name:Methyl (S) - 4 - Methylene - 1 - (benzyloxycarbonyl)pyrrolidine carboxylate
CAS Number:200184-60-7
Molecular formula:C15H17NO4
Molecular Weight:275.3

(S)-1-Benzyl 2-Methyl 4-Oxopyrrolidine-1,2-Dicarboxylate

16217-15-5
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74-95-3 Synthesis

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Methyl (S) - 4 - Methylene - 1 - (benzyloxycarbonyl)pyrrolidine carboxylate

200184-60-7
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Yield:200184-60-7 81%

Reaction Conditions:

Stage #1: 1-benzyloxycarbonyl-4-oxo-L-proline methyl esterwith zinc;zirconocene dichloride in tetrahydrofuran at 20;Inert atmosphere;
Stage #2: 1,1-dibromomethane in tetrahydrofuran at 20 - 30;Inert atmosphere;

Steps:

9.2

Method V: Ketone (1.08 mmol), Zn (566 mg, 8.66 mmol), bis(cyclopentadienyl)zirconium dichloride (380 mg, 1.30 mmol), and THF (2 mL are combined and stirred at rt under nitrogen. Dibromomethane (0.17 mL, 2.44 mmol) is slowly added to the mixture. The internal temperature slowly increased to ca. 30° C. The reaction mixture is stirred for 3 h, and is quenched with water. The solution is extracted twice with ether. The organic layers are combined, dried over sodium sulfate, and concentrated under vacuum. The crude material is purified by column chromatography (SiO₂, 30% ethyl acetate in hexanes).Step 2: (S)-1-Benzyl 2-methyl 4-methylenepyrrolidine-1,2-dicarboxylate is prepared from (S)-1-benzyl 2-methyl 4-oxopyrrolidine-1,2-dicarboxylate following Method V (yield=81%). 1H NMR (300 MHz, CDCl₃) δ 7.42-7.23 (m, 5H), 5.24-4.97 (m, 4H), 4.63-4.48 (m, 1H), 4.22-4.10 (m, 2H), 3.78-3.56 (m, 3H), 3.07-2.88 (m, 1H), 2.72-2.58 (m, 1H).

References:

US2010/22605,2010,A1 Location in patent:Page/Page column 35; 40-41