Twisting the ethano-Tröger's base: the bisamide

Acyclic Twisted Amides

In this contribution, we provide a comprehensive overview of acyclic twisted amides, covering the literature since 1993 (the year of the first recognized report on acyclic twisted amides) through June 2020. The review focuses on classes of acyclic twisted amides and their key structural properties, such as amide bond twist and nitrogen pyramidalization, which are primarily responsible for disrupting n_N to π*_C═O conjugation. Through discussing acyclic twisted amides in comparison with the classic bridged lactams and conformationally restricted cyclic fused amides, the reader is provided with an overview of amidic distortion that results in novel conformational features of acyclic amides that can be exploited in various fields of chemistry ranging from organic synthesis and polymers to biochemistry and structural chemistry and the current position of acyclic twisted amides in modern chemistry.

Asymmetric organocatalysis: an enabling technology for medicinal chemistry

The efficacy and synthetic versatility of asymmetric organocatalysis have contributed enormously to the field of organic synthesis since the early 2000s. As asymmetric organocatalytic methods mature, they have extended beyond the academia and undergone scale-up for the production of chiral drugs, natural products, and enantiomerically enriched bioactive molecules. This review provides a comprehensive overview of the applications of asymmetric organocatalysis in medicinal chemistry. A general picture of asymmetric organocatalytic strategies in medicinal chemistry is firstly presented, and the specific applications of these strategies in pharmaceutical synthesis are systematically described, with a focus on the preparation of antiviral, anticancer, neuroprotective, cardiovascular, antibacterial, and antiparasitic agents, as well as several miscellaneous bioactive agents. The review concludes with a discussion of the challenges, limitations and future prospects for organocatalytic asymmetric synthesis of medicinally valuable compounds.

Influence of halogen size on the supramolecular and energy landscape of the THF solvates of the halogen derivatives of dianthranilide

The detailed description of the crystal structure of the THF solvates of four halogen derivatives of dianthranilide has been reported.

Tröger's Base Twisted Amides: High Amide Bond Twist and N-/O-Protonation Aptitude

Tröger's base twisted amides have emerged as attractive scaffolds to readily achieve substantial nonplanarity of the amide bond in a bicyclic lactam framework. Herein, we report structures and proton affinities of a diverse set of Tröger's base twisted amides and compare them with related nonplanar bridged lactams. The data demonstrate that Tröger's base twisted amides embedded in a [3.3.1] scaffold are among the most twisted bridged lactams prepared to date. Intriguingly, while these amides also favor N-protonation, our data show that the best model for probing N-protonation aptitude in the series of nonplanar amides are less twisted benzofused 1-azabicyclo[3.3.1]nonan-2-one derivatives. This work (1) provides the understanding for future design of nonplanar bridged lactams to directly access N-protonated amide bonds, (2) validates the use of the additive Winkler-Dunitz distortion parameter, and (3) emphasizes the importance of peripheral modification to modulate properties of nonplanar amides.

Chemistry of Bridged Lactams: Recent Developments

Bridged lactams represent the most effective and wide-ranging method of constraining the amide bond in a non-planar conformation. A previous comprehensive review on this topic was published in 2013 (Chem. Rev.2013, 113, 5701–5765). In the present review, which is published as a part of the Special Issue on Amide Bond Activation, we present an overview of the recent developments in the field of bridged lactams that have taken place in the last five years and present a critical assessment of the current status of bridged lactams in synthetic and physical organic chemistry. This review covers the period from 2014 until the end of 2018 and is intended as an update to Chem. Rev.2013, 113, 5701–5765. In addition to bridged lactams, the review covers recent advances in the chemistry of bridged sultams, bridged enamines and related non-planar structures.