Ambient Temperature Nitrogen-Directed Difluoroalkynylborane Carboni−Lindsey Cycloaddition Reactions

Abstract

The in situ generation of alkynyldifluoroboranes in the presence of N-heterocycle substituted tetrazines provides a convenient and direct method for the synthesis of pyridazine difluoroboranes. The reactions proceed in 10 min under ambient conditions and provide the opportunity to assemble unsymmetrical products with complete regiocontrol.

Triphenylamine/tetrazine based π-conjugated systems as molecular donors for organic solar cells

“…s-Tetrazine (Tz) is a strong electron-withdrawing molecule 1,2 which finds many fields of applications such as retro Diels-Alder cyclisation, [3][4][5][6][7][8][9] energetic compounds, 10-16 coordination chemistry, [17][18][19][20][21][22][23][24] electrofluorochromism. [25][26][27][28][29][30][31][32][33][34] Very recently, polymers containing s-tetrazine have been used in organic photovoltaic (OPV) cells [35][36][37][38][39] and there is one example of transistor based on a tetrazine-naphthalene diimide system.…”

Novel s-tetrazine-based dyes with enhanced two-photon absorption cross-section

“…The low LUMO energy of tetrazine derivatives enables inverse demand Diels-Alder cycloaddition reactions as a heterodiene [1][2][3][4][5][6][7][8][9][10][11][12][13] and stabilizes the anionic intermediate that enables aromatic nucleophilic substitution. [14][15][16][17][18][19] Tetrazine derivatives are also used in coordination chemistry [20][21][22][23][24] because they can form complexes with electron-rich metals.…”

A Mechanistic Study of the Lewis Base-Directed Cycloaddition of 2-Pyrones and Alkynylboranes

“…8 This approach has the added advantage of generating compounds with complete regiocontrol. We have developed a mild and regioselective synthesis of aromatic difluoroboranes via the cycloaddition of 2-pyrones with in situ generated alkynyldifluoroboranes.…”

“…In both cases, similar trends were obtained. Alkyne substrates bearing phenyl-, n butyl-and t butyl-substituents reacted rapidly under mild conditions to give the corresponding functionalised aromatic products 7, 12-19 in good to excellent yields (entries [1][2][3][4][5][6][7][8]. The combination of thiazole-substituted 2-pyrone 20 and TMS-alkyne 11 resulted in a slower reaction and this process was conducted at slightly elevated temperature, resulting in some protodesilylation of the product.…”