Direct observation ofo-benzyne formation in photochemical hexadehydro-Diels–Alder (hν-HDDA) reactions

Abstract

Reactive ortho-benzyne derivatives are believed to be the initial products of liquid-phase [4+2]-cycloadditions between a 1,3-diyne and an alkyne via what is known as a hexadehydro-Diels–Alder (HDDA) reaction. The UV/VIS...

Highly Conjugated π‐Systems Arising from Cannibalistic Hexadehydro‐Diels–Alder Couplings: Cleavage of C−C Single and Triple Bonds

“…The excited state lifetime of 9 is shorter than 1 ns and the quantum yield is 26 %. The UV/VIS absorption properties of compounds 8 and 9 , as mentioned before, are of significant importance to another of our publications, in which we report femtosecond transient absorption spectra of the reaction process going from 3 via the benzyne Me‐BZ‐Me to its self‐trapping products 8 and 9 [23] …”

“…The photophysical properties of compounds 8 and 9 are described later in this paper.The absorption spectra are of importance for another of our publications concerningt he direct observation of Me-BZ-Me in solution via femtosecond transient absorption spectroscopy. [23] Last but not least, another species with am olecular weight of 3 2 -2H was detected by HRMS. Single-crystal X-ray diffraction analysis revealed it to be a highly unusualp yrene derivative, better described as ab enzo- As shown in Figure 10, we propose that the initial step in the formation of compound 11 is an HDDA reaction of 3 followed by ar adicalt ype [2+ +2]-addition of the benzyne (Me-BZ-Me)toone alkyne moiety closetothe aryl ring in asecond bisdiyne 3' ( Figure 10, right route).…”

“…The UV/VIS absorption properties of compounds 8 and 9, as mentioned before, are of significant importance to another of our publications, in whichw er eport femtosecond transient absorption spectra of the reaction process going from 3 via the benzyne Me-BZ-Me to its self-trapping products 8 and 9. [23] Benzo[l]indeno[cd]pyrene 11 shows ab road absorption from 360 to 500 nm with am aximum at 413 nm, and the strongest absorption band is located at 280 nm (Figure 16, left). Ab road emission from 450 to 750 nm with two maxima at 493 and 524 nm were detected ( Figure 16, right), and al ifetime of 7.6 ns andq uantum yield of 35 %w ere measured in CH 2 Cl 2 .…”

Celebrating Todd Marder: 65th Birthday and His Contributions to Inorganic Chemistry

“…Todd embraces diversity not only in his group members and numerous local and international collaborators, but also in his research interests [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. For over 30 years, a significant part of his research has focused on metal-catalyzed borylation reactions, metal boryl complexes, mechanisms of borylation and other catalytic reactions [ 1 , 2 , 3 , 4 , 5 , 6 ], and the development of diboron(4) compounds and their chemistry [ 7 , 8 , 9 ].…”

“…One of the diboron(4) compounds he developed in collaboration with Prof. N. C. Norman (Bristol University), namely B 2 neop 2 , is now available commercially world-wide and is produced in multi-ton quantities. He also works in the fields of conjugated organometallic [ 10 ], organoboron [ 11 , 12 , 13 , 14 , 15 , 16 ] and organic materials [ 17 , 18 , 19 ] for linear and nonlinear optics, 2-photon excited fluorescent cell imaging [ 15 ], DNA/RNA/protein sensing [ 16 ], and on crystal engineering using perfluoroarene-arene interactions [ 20 ], among other areas, often combining several areas of his research in a single project.…”