| abstract |
The present invention provides a method for making a compound of formula 1: (See Formula 1) comprising the steps of reacting the compounds of formulas 2 and 3: (See Formula 2) to produce a compound of formula 4: ( See Formula 4) where R1, R2, R3, R4 and R5 are defined as described herein. The compound of formula 4 is then converted to the compound of formula 1. The invention further comprises compound of formulas 3 and 4 and methods for making compounds of formulas 3 and 4. |