TY - JOUR
T1 - Model system for irreversible inhibition of Nek2
T2 - Thiol addition to ethynylpurines and related substituted heterocycles
AU - Lebraud, Honorine
AU - Coxon, Christopher R.
AU - Archard, Victoria S.
AU - Bawn, Carlo M.
AU - Carbain, Benoit
AU - Matheson, Christopher J.
AU - Turner, David M.
AU - Cano, Céline
AU - Griffin, Roger J.
AU - Hardcastle, Ian R.
AU - Baisch, Ulrich
AU - Harrington, Ross W.
AU - Golding, Bernard T.
PY - 2014/1/7
Y1 - 2014/1/7
N2 - Recent studies have shown that irreversible inhibition of Nek2 kinase [(Never in mitosis gene a)-related kinase 2], overexpression of which is observed in several cancers, can be achieved using Michael acceptors containing an ethynyl group, which target the enzyme's cysteine 22 residue lying near the catalytic site. The model studies described herein demonstrate an analogous capture of the ethynyl moiety in a series of ethynyl-heterocycles (e.g. 6-ethynyl-N-phenyl-9H-purin-2-amine) by N-acetylcysteine methyl ester in the presence of 1,4-diazabicyclo[2.2.2]octane in either dimethyl sulfoxide or N,N-dimethylformamide. Kinetic studies showed a 50-fold range in reactivity with 7-ethynyl-N-phenyl-3H-[1,2,3]triazolo[4,5-d]pyrimidin-5-amine being the most reactive compound, whereas 4-ethynyl-N-phenyl-7H-pyrrolo[2,3-d]pyrimidin-2-amine was the least reactive. Studies of the isomeric compounds, 2-(3-((6-ethynyl-7- methyl-7H-purin-2-yl)amino)phenyl)acetamide and 2-(3-((6-ethynyl-9-methyl-9H- purin-2-yl)amino)phenyl)acetamide, revealed the N7-methyl isomer to be 5-fold more reactive than the 9-methyl isomer, which is ascribed to a buttressing effect in the N7-methyl compound. Comparison of the crystal structures of these isomers showed that the ethynyl group is significantly displaced away from the methyl group exclusively in the N 7-methyl isomer with an sp2 bond angle of 124°, whereas the corresponding angle in the N9-methyl isomer was the expected 120°. The results of this study indicate heterocyclic scaffolds that are likely to be more promising for inhibition of Nek2 and other kinases containing a reactive cysteine.
AB - Recent studies have shown that irreversible inhibition of Nek2 kinase [(Never in mitosis gene a)-related kinase 2], overexpression of which is observed in several cancers, can be achieved using Michael acceptors containing an ethynyl group, which target the enzyme's cysteine 22 residue lying near the catalytic site. The model studies described herein demonstrate an analogous capture of the ethynyl moiety in a series of ethynyl-heterocycles (e.g. 6-ethynyl-N-phenyl-9H-purin-2-amine) by N-acetylcysteine methyl ester in the presence of 1,4-diazabicyclo[2.2.2]octane in either dimethyl sulfoxide or N,N-dimethylformamide. Kinetic studies showed a 50-fold range in reactivity with 7-ethynyl-N-phenyl-3H-[1,2,3]triazolo[4,5-d]pyrimidin-5-amine being the most reactive compound, whereas 4-ethynyl-N-phenyl-7H-pyrrolo[2,3-d]pyrimidin-2-amine was the least reactive. Studies of the isomeric compounds, 2-(3-((6-ethynyl-7- methyl-7H-purin-2-yl)amino)phenyl)acetamide and 2-(3-((6-ethynyl-9-methyl-9H- purin-2-yl)amino)phenyl)acetamide, revealed the N7-methyl isomer to be 5-fold more reactive than the 9-methyl isomer, which is ascribed to a buttressing effect in the N7-methyl compound. Comparison of the crystal structures of these isomers showed that the ethynyl group is significantly displaced away from the methyl group exclusively in the N 7-methyl isomer with an sp2 bond angle of 124°, whereas the corresponding angle in the N9-methyl isomer was the expected 120°. The results of this study indicate heterocyclic scaffolds that are likely to be more promising for inhibition of Nek2 and other kinases containing a reactive cysteine.
UR - http://www.scopus.com/inward/record.url?scp=84889006970&partnerID=8YFLogxK
U2 - 10.1039/c3ob41806e
DO - 10.1039/c3ob41806e
M3 - Article
C2 - 24213855
AN - SCOPUS:84889006970
SN - 1477-0520
VL - 12
SP - 141
EP - 148
JO - Organic and Biomolecular Chemistry
JF - Organic and Biomolecular Chemistry
IS - 1
ER -