A simple and efficient synthesis of 1,3,5-tris[2-(3,5-diethynylphenyl)ethynyl]benzene from 1,3,5-triethynylbenzene

Abstract

A concise and convenient three-step process is reported for preparation of 1,3,5-tris[2-(3,5-diethynylphenyl)ethynyl]benzene from 1,3,5-triethynylbenzene and 2-hydroxypropyl group-protected peripheral monomers via a Sonogashira coupling-deprotection reaction sequence. This approach had several advantages, for example high yields, short reaction time, and simple separation procedure. In the key step a modified Sonogashira reaction was developed, under which conditions the coupling of 1,3,5-triethynylbenzene and substituted iodobenzenes proceeded rapidly, giving the desired products in good to excellent yields.

A Covalent Organic Helical Cage with Remarkable Chiroptical Amplification

“…Sonogashira cross‐coupling reaction28 between 1,3,5‐triiodobenzene29 ( 2 ) and three equivalents of enantiopure ( P )‐1,3‐diethynylallene30 ( P )‐ 3 gave tripod ( P,P,P )‐ 4 in 80 % yield, which, after deprotection, provided ( P,P,P )‐ 5 in 90 % yield (Figure 2). Finally, dimerization in pseudo‐high dilution of ( P,P,P )‐ 5 under Breslow conditions,31 CuCl, CuCl 2 in pyridine under Ar, rendered the desired covalent helical cage ( P,P ) 3 ‐ 1 in 55 % yield.…”