Fig 1.
Examples of type II and III inhibitors previously reported.
Fig 2.
Spiro-DKPs as potential α-helix mimetics.
(A) General structure of the target spiro-DKPs with numbering. (B) The side chains of Leu26, Trp23, and Phe19 in the p53 helix.(C) Spiro-DKPs. (D) Superimposition of an Ala-helix (black), with a low energy conformation of a spiro-DKP B (green).
Fig 3.
Retrosynthetic analysis of spiro-DKPs.
Fig 4.
Reagents and reaction conditions: i) PhCHO (1.2 eq.), Et3N (1.2 eq.), NaCNBH3 (1.0 eq.), MeOH, r.t. ii) (CH3)3SiCHN2 (6.4 eq.), MeOH/toluene (1:3), r.t. iii) 4 or 5: R1CHO (1.2–1.5 eq.), Et3N (1.2 eq.), NaCNBH3 (1.0 eq.), MeOH, r.t. iv) Phe-OMe (2.0 eq.), HATU (2.0 eq.), DIPEA (12 eq.), DMF, 60°C, 30 min. 6: iii) Boc2O, 3M NaOH and 1,4-dioxane (1:2, pH~12), r.t. iv) Phe-OMe (2.0 eq.), HATU (2.0 eq.), DIPEA (6.0 eq.), DMF, 60°C, 30 min. v) 4: water, MW, 160°C, 30 min; 5: HCl (1M, aq.)/acetone (1:1), 55°C, 72 h 6: water, MW, 160°C, 90 min.
Fig 5.
Reagents and reaction conditions: i) AA-OMe (1.5–1.7 eq.). HATU (2.0 eq.), DIPEA (6.0 eq.), DMF, 60°C, 30 min. ii) water, MW, 160°C, 70 min. iii) R3-NH2 (1.7–2.0 eq.), PEMB (1.0 eq.), glacial acetic acid (2.3–2.6 eq.), MeOH, r.t. o.n.
Fig 6.
2,5-DKP derivatives docked into the α-helix binding site of MDM2 (PDB code: 4HBM).
(A) and (B) N1 = 4-chlorobenzyl, C3 = Benzyl, N4 = CH2CO2H, C6 = cyclohexyl. (C) N1 = C6 = Phenyl, C3 = benzyl, N4 = CH2CO2H.
Fig 7.
General structures of spiro-2-DKPs and non-spiro-DKPs.
Hydrophobic substituents are indicated by light grey, while hydrophilic substituents are shown in dark grey.
Fig 8.
Synthesis of spiro-2-DKPs 17–21.
Fig 9.
Synthesis of non-spiro-DKPs 22–29.
Fig 10.
Stereochemical assignment of non-spiro-DKPs.
NOE correlations are shown by a double headed arrow.
Fig 11.
N4-Alkylation of spiro-2-DKPs 30–34.
Fig 12.
N4-alkylation of non-spiro-DKPs 35–39.
Fig 13.
N4-Alkylation of non-spiro-DKPs afforded 40–45.
Fig 14.
Ester hydrolysis of non-spiro-DKPs afforded acids 46-53.a
Fig 15.
Ester hydrolysis of 30S and 31S.
Reagents and reaction conditions: i) Conc. HCl (aq.) for R1 = Et, 70°C o.n. For R1 = tBu, r.t. o.n.
Fig 16.
Amidation of 2,5-DKPs afforded 55–58.
Fig 17.
Conformational analysis of 57RS.
(A) Model of two low energy conformations of 57RS; (B) Chemical structure of 57RS with atom numbers; (C) 1H NMR signals from H7 and H6 of 57RS at 25°C and 55°C.
Fig 18.
Boc-deprotection of 55–56 and 58S.
Reagents and reaction conditions: i) TFA:DCM (1:1 v/v), 1h, r.t.
Fig 19.
Reagents and reaction conditions: i) NaBH4 (3.0 eq.), EtOH, r.t., 5 days.
Fig 20.
2,5-DKPs as inhibitors of the MDM2-p53 interaction.