Dr. Aleksey Vasilev talk

Dr. Aleksey Aleksandrov Vasilev, Sofia University (Bulgaria)
E-Z Photoisomerization Stimulated by Triplet-Triplet Annihilation Photon Energy Up-conversion Light 
Multipurpose Building, UAH. June 27th, 12.00.

Vasilev talk

A New Member of the BN-Phenanthrene Family: Understanding the Role of the B—N Bond Position

Alberto Abengózar, David Sucunza, Patricia García-García, Diego Sampedro, Adrián Pérez-Redondo, and Juan J. Vaquero

J. Org. Chem., Article ASAP
DOI: 10.1021/acs.joc.9b00800

3,4-Dihydro-4-aza-3-boraphenanthrene, which shows the highest fluorescence quantum yield of all nonsubstituted BN-phenanthrenes reported to date (ϕF = 0.61), has been synthesized in only three steps (76% overall yield) from easily accessible 1-bromo-2-vinylnaphthalene, along with several substituted derivatives. The reactivity of these previously unknown BN-aromatic compounds toward organolithium compounds and bromine has been studied. This latter reaction affords bromo-substituted compounds that are suitable for further functionalization via Suzuki and Sonogashira couplings, with complete regioselectivity. The optical properties and excited state deactivation mechanisms of selected compounds were studied using computational methods.

Synthesis, Functionalization, and Optical Properties of 1,2-Dihydro-1-aza-2-boraphenanthrene and Several Highly Fluorescent Derivatives

Alberto Abengózar, Patricia García-García, David Sucunza, Diego Sampedro, Adrián Pérez-Redondo, and Juan J. Vaquero

Org. Lett., Article ASAP
DOI: 10.1021/acs.orglett.9b00448

Previously unknown 1,2-dihydro-1-aza-2-boraphenanthrene has been synthesized in only three steps from 2-bromo-1-vinylnaphthalene. The reactivity of this new BN-phenanthrene, and of several substituted derivatives, has been tested against bromine and organolithium compounds. Bromination proceeded with complete regioselectivity, affording bromo-substituted compounds suitable for further functionalization via cross-coupling reactions. This new family of BN-phenanthrenes exhibits a substantial increase in the quantum yield (up to ϕ_F = 0.93) with respect to phenanthrene.

Regiodivergent electrophilic cyclizations of alkynylcyclobutanes for the synthesis of cyclobutane-fused O-heterocycles

María Soledad Garre, David Sucunza, Enrique Aguilar, Patricia García-García, and Juan J. Vaquero

J. Org. Chem., Article ASAP
DOI: 10.1021/acs.joc.9b00618

Cyclobutane-fused dihydropyrans and methylenetetrahydrofurans are highly interesting cores found in numerous natural products. Both these cores are selectively prepared from a common alkynylcyclobutane precursor bearing an appended hydroxyl group herein. Thus, cyclobutane-fused dihydropyrans can be obtained by a selective 6-endo-dig iodocyclization, whereas gold-catalyzed 5-exo-dig cycloisomerization provides the bicyclic core containing a methylenetetrahydrofuran moiety as major product. Several cyclobutane-fused O-heterocycles with diverse substitution are synthesized following the reported methodology.

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