Design of Dual EP2/EP4 Antagonists through Scaffold Merging of Selective Inhibitors.

Prostaglandin E2 (PGE2) plays a key role in various stages of cancer. PGE2 signals through the EP2 and the EP4 receptors, promoting tumorigenesis, metastasis, and/or immune suppression. Dual inhibition of both the EP2 and the EP4 receptors has the potential to counteract the effect of PGE2 and to result in antitumor efficacy. We herein disclose for the first time the structure of dual EP2/EP4 antagonists. By merging the scaffolds of EP2 selective and EP4 selective inhibitors, we generated a new chemical series of compounds blocking both receptors with comparable potency. In vitro and in vivo profiling suggests that the newly identified compounds are promising lead structures for further development into dual EP2/EP4 antagonists for use in cancer therapy.

Naphthalen-1-yl-(4-pentyloxynaphthalen-1-yl)methanone: a potent, orally bioavailable human CB1/CB2 dual agonist with antihyperalgesic properties and restricted central nervous system penetration.

Selective activation of peripheral cannabinoid CB1 receptors has the potential to become a valuable therapy for chronic pain conditions as long as central nervous system effects are attenuated. A new class of cannabinoid ligands was rationally designed from known aminoalkylindole agonists and showed good binding and functional activities at human CB1 and CB2 receptors. This has led to the discovery of a novel CB1/CB2 dual agonist, naphthalen-1-yl-(4-pentyloxynaphthalen-1-yl)methanone (13), which displays good oral bioavailability, potent antihyperalgesic activity in animal models, and limited brain penetration.

Development of a third-generation total synthesis of (+)-discodermolide: an expedient Still-Gennari-type fragment coupling utilizing an advanced beta-ketophosphonate.

[structure: see text] A novel total synthesis of the complex polyketide discodermolide, a promising anticancer agent of marine sponge origin, has been completed in 11.1% overall yield over 21 linear steps. This third-generation approach features an unprecedented Still-Gennari-type HWE olefination reaction between advanced C1-C8 beta-ketophosphonate 61 and C9-C24 aldehyde 7, introducing the (8Z)-alkene with 10:1 selectivity. The stereotetrad found in the C1-C8 subunit 61 was established via a highly diastereoselective boron-mediated aldol reaction/in situ reduction between ketone (S)-8 and 3-benzyloxypropanal. The (7S)-configuration was installed by the reduction of enone 73 with K-Selectride.

A second-generation total synthesis of (+)-discodermolide: the development of a practical route using solely substrate-based stereocontrol.

A novel total synthesis of the complex polyketide (+)-discodermolide, a promising anticancer agent of sponge origin, has been completed in 7.8% overall yield over 24 linear steps, with 35 steps altogether. This second-generation approach was designed to rely solely on substrate control for introduction of the required stereochemistry, eliminating the use of all chiral reagents or auxiliaries. The common 1,2-anti-2,3-syn stereotriad found in each of three subunits, aldehyde 9 (C(1)-C(5)), ester 40 (C(9)-C(16)), and aldehyde 13 (C(17)-C(24)), was established via a boron-mediated aldol reaction of ethyl ketone 15 and formaldehyde, followed by hydroxyl-directed reduction to give 1,3-diol 14. Alternatively, a surrogate aldehyde 22 was employed for formaldehyde in this aldol reaction, leading to the beta-hydroxy aldehyde 20 as a common building block, corresponding to the discodermolide stereotriad. Key fragment unions were achieved by a lithium-mediated anti aldol reaction of ester 40 and aldehyde 13 under Felkin-Anh control to provide (16S,17S)-adduct 51 and a boron-mediated aldol reaction between enone 10 and aldehyde 9, exploiting unprecedented remote 1,6-stereoinduction, to give the (5S)-adduct 57.

Total synthesis of (+)-discodermolide: an improved endgame exploiting a Still-Gennari-type olefination with a C1-C8 beta-ketophosphonate fragment.

[structure: see text] An improved, third-generation, total synthesis of (+)-discodermolide, a potent microtubule-stabilizing anticancer agent of marine sponge origin, is achieved in 11.1% yield over 21 steps. Key steps include a Still-Gennari HWE olefination, performed using NaH as the base, between C1-C8 beta-ketophosphonate 7 and C9-C24 aldehyde 8, introducing the (8Z)-alkene with 10:1 selectivity, and K-Selectride reduction of the derived enone 16, installing the (7S)-configuration.

1,6-asymmetric induction in boron-mediated aldol reactions: application to a practical total synthesis of (+)-discodermolide.

By relying solely on substrate-based stereocontrol, a practical total synthesis of the microtubule-stabilizing anticancer agent (+)-discodermolide has been realized. This exploits a novel aldol bond construction with 1,6-stereoinduction from the boron enolate of (Z)-enone 3 in addition to aldehyde 2. The 1,3-diol 7 is employed as a common building block for the C(1)-C(5), C(9)-C(16), and C(17)-C(24) subunits. [reaction--see text]