CPC C07D 401/12 (2013.01) [B01J 23/72 (2013.01); B01J 27/122 (2013.01); C07D 231/12 (2013.01); C07D 231/18 (2013.01)] | 32 Claims |
1. A process for preparation of a compound of formula II,
wherein R2 is F, C1-C4 alkyl, or C1-C4 haloalkyl,
R3 is, F, C1-C4 alkyl, or C1-C4 haloalkyl,
R4 is C1-C4 alkyl,
R6 is H or a protecting group or a salt thereof, and
R7 is H, Cl or trialkylsilyl,
comprising the steps of:
a) reacting a compound of formula VII with elemental sulfur in the presence of a base, a catalyst and a reducing agent to give a compound of formula VI;
wherein R3, R4 and R7 are as defined above and L1 is a leaving group;
b) reacting the compound of formula VI with a compound of formula VIII, to give a compound of formula V;
wherein L2 is a leaving group and R3, R4, R6 and R7 are as defined above; and
c) converting the compound of formula V to the compound of formula II.
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