An attempt to consider cooperativity in helical-sense preferences induced in fused macrocycles

Abstract

We synthesized bis and tris(macrocycle)s in which a two- or threefold macrocycle was fused and each adopted twisted forms with M- or P-helicity. According to the sense of twisting in...

Study of optical rotation based on the molecular structure in fused oligomers of macrocycles

“…If only a single pair of diastereomeric (pseudo-enantiomeric) conformers with M - or P -helicity could be present in the solution ( Scheme 1b , controlled), that would be suitable for estimating the population as a diastereomeric ratio ( M N / P N ), as with a monomeric case ( N = 1). This was the case for 2, 10 4, 11 5, 10, 12 and 11. 12 Fortunately, the diastereomeric ratio was quantitatively estimated for 2, 4, and 5.…”

“…S14†), we reported that the diastereomeric ratio (α/β) induced at 223 K in chloroform was estimated to be 2.3 for M - 1 and P - 1 , 4.7 for MM - 2 and PP - 2 , and 9.9 for MMM - 4 and PPP - 4 by linear extrapolation. 11 In a similar manner, the value of α/β was estimated to be ca. 51 for MMMM - 5 and PPPP - 5 (Fig.…”

“…The term can cover another form of oligomers; 5–8 for example, in which the monomer is a macrocycle arranged in a rotation-restrained manner. 6–8 We are particularly interested in a unique case in which the macrocyclic monomer is variant in terms of chirality 9–13 (Scheme 1b). The conformational control of such a fused oligomer of macrocycles would be attained by an accumulative result of multiple controls of local conformation ( e.g.…”

“…, dynamic chiral sense of twisting) in each macrocyclic element since the linkage is invariant. In such fused oligomers of macrocycles, there are cases where all elements prefer the same sense throughout the entire molecule (for descriptive purposes, we call this a “homochiral” situation) 10–12 or different senses coexist (“heterochiral” situations) 13 in a molecule. Such conformational interinfluence could be a driving force for a molecule to predominantly adopt a particular conformation among multiple conformations.…”