	US 11,939,332 B2
	Synthesis of coelenterazine
Rajagopala Reddy Duvvuru, Hyderabad (IN); Rama Bhatt, Newcastle, WA (US); and Anil Kumar, Puyallup, WA (US)
Assigned to INTERNATIONAL PAPER COMPANY, Memphis, TN (US)
Filed by International Paper Company, Memphis, TN (US)
Filed on Nov. 4, 2020, as Appl. No. 17/089,573.
Application 17/089,573 is a division of application No. 16/457,788, filed on Jun. 28, 2019, granted, now 11,008,326.
Claims priority of provisional application 62/845,189, filed on May 8, 2019.
Claims priority of provisional application 62/692,485, filed on Jun. 29, 2018.
Prior Publication US 2021/0070762 A1, Mar. 11, 2021
Int. Cl. C07D 487/04 (2006.01); B01J 20/22 (2006.01); B01J 31/24 (2006.01); C07B 51/00 (2006.01)

CPC C07D 487/04 (2013.01) [B01J 20/22 (2013.01); B01J 31/2404 (2013.01); B01J 2531/824 (2013.01); C07B 51/00 (2013.01)]

9 Claims

1. A method of making coelenterazine, comprising:

(a) reacting 3-benzylpyrazin-2-amine (25) with N-bromosuccinimide to provide 3-benzyl-5-bromopyrazin-2-amine (2);

(b) reacting the 3-benzyl-5-bromopyrazin-2-amine (2) in two sequential steps to provide 4-(5-amino-6-benzylpyrazin-2-yl)phenol (7) (coelenteramine); and

(c) coupling the 4-(5-amino-6-benzylpyrazin-2-yl)phenol (7) with silyl-protected 1,1-diethoxy-3-(4-hydroxyphenyl)propan-2-one to provide coelenterazine, or a salt thereof.