(2S,5S)-2,5-DIBENZYL-PIPERAZINE synthesis

5synthesis methods

Product Name:(2S,5S)-2,5-DIBENZYL-PIPERAZINE
CAS Number:79982-83-5
Molecular formula:C18H22N2
Molecular Weight:266.38

2862-51-3 Synthesis

2862-51-3
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79982-83-5
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Yield:79982-83-5 82%

Reaction Conditions:

Stage #1: (3S,6S)-3,6-dibenzylpiperazine-2,5-dionewith borane-THF in tetrahydrofuran at 0;Reflux;
Stage #2: with methanol;palladium 10% on activated carbon in tetrahydrofuran at 20; for 12 h;

Steps:

19 (2S,5S)-2,5-Bis(phenylmethyl)piperazine 21

To a vigorously stirred suspension of (3S,6S)-3,6-bis(phenylmethyl)- piperazine-2,5-dione (4.30 g, 14.60 mmol) in THF (72 mL), BH₃^{FontWeight="Bold" FontSize="10"}THF (1 M solution in THF, 87 mL, 84 mmol) was added dropwise at 0°C. The mixture was stirred for 1 h, warming to r.t and heated to reflux for 2 h The solution was filtered, cooled at 0°C, carefully quenched with methanol (20 mL), and then concentrated under reduced pressure. The residual crystalline material was dissolved in methanol (17 mL) and THF (7 mL), and then a suspension of 10% palladium on carbon (177 mg, 50% wet) in methanol (17 mL) was added. The mixture was stirred for 12 h at r t. The crude reaction mixture was filtered and concentrated under reduce pressure. Purification by flash column chromatography (8:92 methanoLchloroform) gave 21 as colourless oil (3.20 g, 82%); R_f 0.51 (5:95 methanol:chloroform); IR (v, neat/cm^"1): 3320, 3020, 2700, 1455, 1305 1 190, 990, 742; H NMR (500 MHz, CDCI₃) δ: 1 .59 (br s, 2H, NH), ), 2.79-3.03 (overlap m, 10H, ArCH₂, NHCH₂, NHCH), 7.21 -7.35 (m, 10H, ArH); ³C NMR (125.8 MHz, CDCI₃) δ: 38.1 (2 ArCH₂), 47.5 (2 NHCH₂), 55.2 (2 NHCH), 125.7 (2 CH) 128.0 (4 x CH), 128.7 (4 x CH), 138.9 (2 ^χ C); HRMS (Fl)⁺: m/z calcd for C₁₈H₂₂N₂ [M⁺ 266.1775, found 266.1783.