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Table 1 Screening of solvent for the synthesis of compound 4

From: Improved one-pot synthesis of N, N-diisopropyl-3-(2-Hydroxy-5-methylphenyl)-3-phenyl propanamide; a key intermediate for the preparation of racemic Tolterodine

Entry Coumarin Amine Solvent Temparature Yield (%)c
1. 2 DIPAa DCM Reflux No reaction
2. 2 DIPA THF Reflux No reaction
3. 2 DIPA ACN Reflux No reaction
4. 2 DIPA ACN Sealed tubeb 15
5. 2 DIPA Methanol 25-30°C 15
6. 2 DIPA Methanol Reflux 15
7. 2 DIPA Ethanol Reflux 10
8. 2 DIPA Toluene Reflux 30
9. 2 DIPA Diisopropylether 25-30°C 53
  1. aN.N-diisopropylamine (DIPA), for all the above reactions 5 mole equivalents of DIPA used. bpressure reaction performed at 110°C. cisolated yields.