Crossed McMurry Coupling Reactions for Porphycenic Macrocycles: Non‐Statistical Selectivity and Rationalisation

Abstract

Crossed McMurry reactions of bifuran- or bithiophenedicarbaldehydes with bipyrroledicarbaldehydes have been studied for the first time. Only those porphycenic macrocycles derived from homocoupled McMurry products were formed. The results are explained by using both density functional theory and electron propagator computations to model the electron affinity of the dialdehyde starting materials. It was predicted that bifuran\bithiophene cross-coupling would indeed occur, and this was demonstrated by the first synthesis of a novel dioxa,dithio hetero-porphycenoid annulene. This approach will allow the prior identification of viable substrates for related crossed McMurry reactions.

Porphycenes and Related Isomers: Synthetic Aspects

“…The conception of porphycenes as bridged [18]annulenes encouraged the preparation of porphycene analogues constructed by the substitution of nitrogen and carbon atoms with other heteroatoms. [34][35][36][37]39 This novel family of compounds is termed porphycene heteroanalogues. 6 The first example of this type of macrocycle was reported in 1988, not long after the first report on porphycenes.…”

“…The authors rationalized this result in terms of steric interaction between the heteroatoms of the rings after the first coupling of the aldehydes (i.e., furan−furan coupling is favored over furan− thiophene coupling). 35 To elucidate the factors that affect the outcome of mixed couplings, in 2015, Bebbington and co-workers 36 studied the reductive cross-coupling of biheteroaryl dialdehydes, such as 253 and 254, with bipyrrolic dialdehydes. Interestingly, only homodimers were obtained.…”

“…The electronic characteristics and the balance between global (18 π-electrons) and local (inherent to the heterocycle, 6 π-electrons) aromaticity of the resulting macrocycles greatly depend on the nature of the incorporated heterocycle. To date, the list of heterocycles replacing pyrrole includes furan − and thiophene − (Table ) and imidazole , and thiazole (Table ).…”

“…To elucidate the factors that affect the outcome of mixed couplings, in 2015, Bebbington and co-workers studied the reductive cross-coupling of biheteroaryl dialdehydes, such as 253 and 254 , with bipyrrolic dialdehydes. Interestingly, only homodimers were obtained.…”

Edge Decoration of Anthracene Switches Global Diatropic Current That Controls the Acene Reactivity

“…The anthracene derivatives were obtained with the application of catalytic processes with transition metals. The connection between acene and heterocyclic subunits was achieved with Suzuki–Miyaura coupling followed by the McMurry reaction as a convenient way to form alkenes utilized in the synthesis of different macrocycles armed with a CC double bond. , …”