| 主权项 |
1. A process comprising the step of dehydrating a compound of Formula (I): to form a compound of Formula (II): wherein R1 is —CH═CH—R8 or —CH2—CH═CH—R9; R2 is C1-C4-alkyl; R3 is H, C1-C4-alkyl, benzyl, or -phenyl-(R10)x; each R4 is independently H, or C1-C4-alkyl; each R5 and each R6 are independently H, C1-C4-alkyl, —O—C1-C4-alkyl, or —S—C1-C4-alkyl; R7 is R8 or —CH2—R9; R8 is H, C1-C4-alkyl, or -phenyl-(R10)x; R9 is H, C1-C3-alkyl, or -phenyl-(R10)x; each R10 is independently halo, C1-C6-alkyl, —O—C1-C4-alkyl, or —S—C1-C4-alkyl; and each x is independently 0, 1, or 2 wherein the process is carried out in the presence of an organic base and a dehydrating agent selected from Tf2O or P2O5.
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