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18th November 2016 @ 19:12
Reaction Scheme [data]19985[/data]   Reagents used Reagents Equivalence corrections Quantity (mg / mL) mmol Molecular Weight 2-Bromobenzaldehyde 1 200 mg 0.13 mL 1.08 185.02 Toluene - 5 mL 47.21 92.14 Pyrrolidine   2.6 200 mg 0.24 mL 2.81 71.12 Rac-BINAP   0.009 6.20 mg 9.96x10-3 622.67 CsCO3   0.8 282.00 mg 0.86 325.82 Pd(OAc)2   0.008 2.00 mg 8.91x10-3 224.51 DCM - 70 mL       Procedure To 2-bromobenzaldehyde (200 mg, 1.08 mmol) in toluene (5 mL) was added pyrrolidine (0.24 mL, 2.81 mmol), rac-BINAP (6.20 mg, 9.96x10-3 mmol), CsCO3 (282.00 mg, 0.86 mmol) and Pd(OAc)2 (2.00 mg, 8.91x10-3 mmol) sequentially. The reaction was purged with N2for 15 minutes, then heated for 21 hours at reflux.  After this time, TLC analysis (50% EtOAc/pet. Ether) was undertaken. It could be seen that starting material was still present, but the reaction was quenched anyway. The reaction was poured onto half-saturated K2CO3 solution, and extracted into CH2Cl2. The combined organic phases were washed with brine, dried (MgSO4), filtered and the solvent removed in vacuo to give an orange oil (343 mg). 1H NMR showed that the reaction was a complex mixture, still containing starting material therefore an alternative route was sought.    [data]20063[/data] Leaving the reaction mixture to reflux under inert nitrogen atmosphere.    [data]20065[/data] Mixture left to stir and reflux for 21 hours.   [data]20067[/data] After refluxing for 21 hours, 35 minutes. A change in colour was noticed as it turned to dark brown with residue.    [data]20069[/data] Third TLC plate under 50-50% mobile phase: after the use of more dilute 2-bromobenzaldehyde a better separation was seen under UV (254nm)   [data]20071[/data] Extracted combined organic phases that was rotary evaporated   Analysis:  1H NMR data of end product  [data]20073[/data]   References Constantin Rabong, Christian Hametner and Kurt Mereiter, et al., Heterocycles, 2008, 75, 813.  
Attached Files
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BH-organic phases.jpg
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