CPC C07C 51/04 (2013.01) [C07C 59/285 (2013.01); C07B 2200/13 (2013.01)] | 20 Claims |
1. A method of preparing a pharmaceutical material comprising a compound of formula (V):
![]() the method comprising:
(a) contacting ethyl isobutyrate with a substituted 5-chloropentane in the presence of a first base to form a compound of formula (I):
![]() wherein the substituted 5-chloropentane is selected from the group consisting of 1-bromo-5-chloropentane and 1-iodo-5-chloropentane;
(b) contacting the compound of formula (I) with a salt of formula [M]+[X]−to form a compound of formula (II):
![]() wherein [M]+ is selected from the group consisting of Li+, Na+ and K+, and [X]− is I−;
(c) contacting the compound of formula (II) with toluenesulfonylmethyl isocyanide in the presence of a second base to form a first intermediate, and contacting the first intermediate with an acid to form a compound of formula (IV):
![]() and
(d) contacting the compound of formula (IV) with a reducing agent to form a second intermediate, and contacting the second intermediate with a hydrolyzing base to form a compound of formula (V),
wherein the pharmaceutical material comprises 0.0001% to less than or equal to 0.15% of the compound of formula (VI):
![]() based on the total weight of the pharmaceutical material.
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