Transient [3,3] Cope rearrangement of 3,3-dicyano-1,5-dienes: computational analysis and 2-step synthesis of arylcycloheptanes.

A simple and modular route to arylcycloheptene scaffolds is reported. The two-step route from Knoevenagel adducts and allylic electrophiles is made possible through the design of a Cope rearrangement that utilizes a "traceless" activating group to promote an otherwise thermodynamically unfavorable transformation. Experimentally, the [3,3] rearrangement occurrs transiently at room temperature with a computed barrier of 19.5 kcal mol-1, which ultimately allows for three-component bis-allylation. Ring-closing metathesis delivers the arylcycloheptane and removes the activating group. This report describes the design and optimization of the methodology, scope and mechanistic studies, and computational analysis

Bis[1-(2-eth­oxy­phen­yl)-3-(4-nitro­phen­yl)triazenido]mercury(II)

In the title compound, [Hg(C14H13N4O3)2], the central Hg atom (site symmetry 2) is six-coordinated by two tridentate 1-(2-eth­oxy­phen­yl)-3-(4-nitro­phen­yl)triazenide ligands through two N and one O atoms. The mononuclear complex mol­ecules are connected into two parallel chains by inter­molecular C—H⋯O hydrogen-bonding inter­actions. These chains are connected to each other by face-to-edge C—H⋯π inter­actions between the CH of the ethoxy groups and the aromatic rings, resulting in a two-dimensional architecture in the ac plane

Factors Governing and Application of the Cope Rearrangement of 3,3-Dicyano-1,5-dienes and Related Studies

Cope and co-workers reported the [3,3] rearrangement of 3,3-dicyano-1,5-dienes in the early 1940s (“The Cope rearrangement”). However, these original substrates have remained largely unstudied until recently. Herein we explore styrene-deconjugating Cope rearrangements, a diastereoselective Cope rearrangement/deconjugative α-allylation sequence, and factors governing α- vs γ-allylation regioselectivity of Knoevenagel adduct allyl anions. Ultimately, these studies result in the synthesis of diverse and functionally dense polycycloalkane frameworks from abundant reagents using simple chemistry

Overcoming Kinetic and Thermodynamic Challenges of Classic Cope Rearrangements

Systematic evaluation of 1,5-dienes bearing 3,3-electron-withdrawing groups and 4-methylation results in the discovery of a Cope rearrangement for Meldrum's acid-containing substrates that have unexpectedly favorable kinetic and thermodynamic profiles. The protocol is quite general due to a concise and convergent synthesis from abundant starting materials. Furthermore, products with an embedded Meldrum's acid moiety are prepared, which, in turn, can yield complex amides under neutral conditions. We have now expanded the scope of the reductive Cope rearrangement, which, via chemoselective reduction, can promote thermodynamically unfavorable [3,3] sigmatropic rearrangements of 3,3-dicyano-1,5-dienes to form reduced Cope rearrangement products. The Cope rearrangement is found to be stereospecific and can yield enantioenriched building blocks when chiral, nonracemic 1,3-disubstituted allylic electrophiles are utilized. We expand further the use of Cope rearrangements for the synthesis of highly valuable building blocks for complex- and drug-like molecular synthesis

The future of scientific leadership is interdisciplinary: The 2019 CAS Future Leaders share their vision

For the last decade, the CAS Future Leaders program has gathered early-career scientists from across the globe based on their outstanding accomplishments in the field of chemistry to provide support to participants in cultivating their own voices and futures in scientific leadership. The goal of the program has been to empower early-career scientists like us to begin to shape our own future leadership roles, from learning to convey effective speech by developing our own research stories to growing to be better mentors for the next generation of future leaders. In 2019, to honor the 10th anniversary of the program, the CAS Future Leaders program encompassed essential leadership skills divided into five topics, namely, storytelling, insights, strategies, perspectives, and impact, some of which were new to the program this year. However, what was not new to the program was an emphasis on the potential global impact that this program could make. To do this, the program brought together in this cohort 29 post-docs and graduate students, from 16 countries. A staple of this program is not only the breadth of countries that are represented but also the many facets of chemistry that are represented as demonstrated later in the article. One reason for this is that a leader in the sciences will need to be open to innovations across discipline and geographical boundaries, something that we explored a lot during our time together