| 主权项 |
1. A process comprising wherein (i) reacting compound (I) with compound (II) in step a to produce compound (III), wherein said reacting is conducted in a polar protic solvent under ambient pressure; followed by (ii) cyclizing compound (III) using a dehydrating agent to produce compound (IV) wherein said dehydrating agent is selected from the group consisting of POCl3, H2SO4, SOCl2, P2O5, polyphosphoric acid, p-toluene sulfonic acid, trifluoroacetic anhydride, or a mixture thereof, and wherein said cyclizing is conducted at ambient pressure, and temperatures from 60° C. to 120° C.; wherein (A) R1 is H; (B) R2 is a (C1-C6)alkyl; (C) R3 is H or (C1-C6)alkyl; and (D) R4 is H, (C1-C6)alkyl, or cyclopropyl. |
