US 11,708,382 B2
Process for the preparation of highly pure Crisaborole
Rupa Sudhir Merchant, Mumbai (IN); Aditya Sudhir Merchant, Mumbai (IN); Piyushkumar Bhikhalal Limbad, Ahmedabad (IN); Akshay Madhubhai Pansuriya, Amreli (IN); Bhavin Madhavjibhai Vavaiya, Ahmedabad (IN); and Jasmin Jaysukhlal Faldu, Ahemdabad (IN)
Assigned to Halcyon Labs Private Limited, Mumbai (IN)
Filed by Halcyon Labs Private Limited, Mumbai (IN)
Filed on Apr. 7, 2021, as Appl. No. 17/224,483.
Application 17/224,483 is a division of application No. 16/960,122, granted, now 11,014,944, previously published as PCT/IN2019/050002, filed on Jan. 1, 2019.
Claims priority of application No. 201821000974 (IN), filed on Jan. 9, 2018.
Prior Publication US 2021/0246150 A1, Aug. 12, 2021
Int. Cl. C07F 5/02 (2006.01); C07C 253/30 (2006.01); C07C 255/54 (2006.01)
CPC C07F 5/025 (2013.01) [C07C 253/30 (2013.01); C07C 255/54 (2013.01)] 4 Claims
 
1. A process for preparation of crisaborole of a compound of formula (I) through use of a compound of formula (IV), (III) or (II), comprising:
reacting the compound of formula (IV) with a borylation reagent to provide the compound of formula (III);
optionally transesterifying the compound of formula (III) with diethanolamine in suitable solvent to provide the compound of formula (II);
deprotecting and cyclizing the compound of formula (II) or (III) for the preparation of crisaborole of formula (I); and
wherein the compound of formula (IV) is,

OG Complex Work Unit Chemistry
where X=Cl, Br, I, F or Triflate,
wherein the compound of formula (III) is,

OG Complex Work Unit Chemistry
wherein the compound of formula (II) is,

OG Complex Work Unit Chemistry
wherein the compound of formula (I) is,

OG Complex Work Unit Chemistry