Ring Construction by 1,1‐Carboboration; Making Anthracene Derivatives from a Tetra(alkynyl)benzene

Abstract

Dedicated to Professor Peter Kündig on the occasion of his 75th birthday. 1,2,4,5-Tetrakis(trimethylsilylethynyl)benzene reacted with two molar equivalents of the boranes RÀ B(C 6 F 5 ) 2 (R = C 6 F 5 , Me, Ph) in a series of sequential 1,1-carboboration reactions to give ca. 1 : 1 mixtures of the two-fold benzannulated products, namely the respective C 2h and C 2v symmetric tetra-silyl, bis-boryl substituted anthracenes. Their active B(C 6 F 5 ) 2 substituents were used for consecutive Suzuki-Miyaura CÀ C coupling reactions to give boron-free phenyl or 2-pyridyl substituted anthracene products.

Straightforward and regiospecific synthesis of 1,3,5,7-tetra-arylated acene bearing different aryl groups

“…Multiple-arylated acenes (MAAs), in which multiple aryl groups are introduced into acenes, are promising molecules with potential applications in organic electronic materials. [1][2][3][4][5][6][7][8][9][10] MAAs, such as 2,6-diphenylanthracene 11,12 and rubrene, 9,10 have high carrier mobility due to their rigid backbone and stability due to extended π-conjugation through single bonds. 13 The development of MAAs can be accelerated by establishing an efficient synthetic method that allows for the introduction of aryl groups more conveniently and precisely.…”

“…Recently, we reported a Pdcatalysed cross-dehydrogenative coupling (CDC) reaction for the synthesis of MAAs containing two polyfluoroarene groups (Scheme 1a). 14 This reaction proceeds at the sterically vacant positions (2,6,7) of acene, in contrast to the general regioselectivity of Pd-catalysed C-H functionalization at the 1-position. [15][16][17][18][19][20] However, the regioselective control of the second polyfluoroarylation is a synthetic challenge, and the reaction leads to a mixture of 2,6 and 2,7-arylated anthracenes.…”