1,3-dibenzylpiperazine-2,5-dione

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a 0° C. suspension of dione 6 (1.38 g, 4.7 mmol) in dry THF (120 mL) was added LiAlH4 (0.713 g, 18.8 mmol) in two portions. The mixture was maintained on ice for 15 min, then the reaction was heated at reflux for 2.5 h. The solution was cooled and stirred for an additional 19 h then the excess LiAlH4 was quenched by the careful, sequential addition of 0.7 mL water, 1.3 mL 4 M NaOH and 0.7 mL water. The solids that formed will filtered (Celite) and the filtrate concentrated to provide 7 as a pale colored solid (1.29 g, 103%, with THF) that slowly formed from an oil. 1H NMR (400 MHz, CDCl3): δ 1.93 (m, triplet shape, 1H), 2.11 (td, J=2.9, 11.0 Hz, 1H, overlapped with bs, NH, 1H), 2.58 (dd, 8.8, 13.2 Hz, 1H), 2.70-2.77 (m, 2H), 2.79-2.87 (m, 2H), 2.92 (dt, J=2.3, 11.7 Hz, 1H), 3.02 (m, 1H), 3.51 (dd, AB pattern, J=12.8 Hz, 2H), 7.18-7.33 (m, 10H); 13C NMR (100 MHz, CDCl3): δ 40.7, 45.6, 53.3, 56.2, 59.6, 63.3, 126.3, 127.0, 128.1, 128.4, 129.2, 137.9, 138.5. HRMS Calcd. for [C18H22N2+H+]: 267.1861. Found 267.1869. The mixture was maintained on ice for 15 min the reaction was heated at reflux for 2.5 h The solution was cooled the excess LiAlH4 was quenched by the careful, sequential addition of 0.7 mL water, 1.3 mL 4 M NaOH and 0.7 mL water The solids that formed will filtered (Celite) the filtrate concentrated

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a 0° C. solution of dipeptide 5 (2.18 g, 5.11 mmol) in methanol (30 mL) was slowly added excess thionyl chloride (1.9 mL). The solution stirred at ambient temperature for 2.5 h. The solvent was evaporated and the residue was triturated with ˜30 mL of ether, producing a white solid that was collected by filtration. The solid was dissolved in methanol (40 mL) and treated with ammonium hydroxide (29%, 10 mL) and then stirred for 18 h followed by concentration. The solid residue was partitioned between saturated NaHCO3 (40 mL), water (20 mL) and CHCl3:isopropyl alcohol, 4:1 (40 mL). The organic phase was separated and the aqueous phase extracted with CHCl3:isopropyl alcohol, 4:1 (3×40 mL). The combined organic phases were dried (K2CO3) and concentrated to afford 6 as a white solid (1.382 g, 92% yield). 1H NMR (400 MHz, CDCl3): δ 2.99 (d, part of AB pattern, J=17.6 Hz, 1H), 3.17 (m, AB pattern, 2H), 3.52 (d, part of AB pattern, J=17.6 Hz, 1H), 4.35 (m, 1H), 4.48 (m, AB pattern, J=14.7 Hz, 1H), 6.39 (bs, NH, 1H), 7.13-7.35 (m, 10H, overlapped with CDCl3); 13C NMR (100 MHz, CDCl3): δ 40.5, 48.2, 49.6, 56.4, 127.4, 128.1, 128.59, 128.63, 128.8, 130.0, 134.65, 134.68, 165.2, 166.3. To a 0° C. The solvent was evaporated the residue was triturated with ˜30 mL of ether producing a white solid that was collected by filtration The solid was dissolved in methanol (40 mL) treated with ammonium hydroxide (29%, 10 mL) stirred for 18 h followed by concentration The solid residue was partitioned between saturated NaHCO3 (40 mL), water (20 mL) and CHCl3 The organic phase was separated the aqueous phase extracted with CHCl3 The combined organic phases were dried (K2CO3) concentrated