Controlled Access to C₁‐Symmetrical Cyclotriveratrylenes (CTVs) by Using a Sequential Barluenga Boronic Coupling (BBC) Approach

Abstract

We describe here a controlled approach to C1‐symmetrical cyclotriveratrylenes (CTVs). In this approach dimers are synthesized through Barluenga boronic coupling (BBC) and after borylation, the last aromatic ring is introduced by a second BBC. After functional transformations of the trimers, the CTVs are formed using intramolecular SEAr.

Synthesis and Physicochemical Properties of Cryptophazane—A Soluble and Functionalizable C1‐Symmetrical Cryptophane

“…On the other hand, the intermediate 3 was prepared using a known Barluenga Boronic Coupling (BBC) between (2-bromo-4-methoxybenzyl)-toluenesulfonylhydrazone and 3-methoxyphenylboronic acid. [35] Then, a Buchwald-Hartwig Amination (BHA) between compound 2 and 3 afforded the trimer 4 in 97 % yield. After deprotection of 4 using TBAF in THF, cyclization was performed using perchloric acid, affording the expected CTV 6 in 89 % yield.…”

“…On one hand, the intermediate 2 was obtained through protection of alcohol 1 . On the other hand, the intermediate 3 was prepared using a known Barluenga Boronic Coupling (BBC) between (2‐bromo‐4‐methoxybenzyl)‐toluenesulfonylhydrazone and 3‐methoxyphenylboronic acid [35] . Then, a Buchwald–Hartwig Amination (BHA) between compound 2 and 3 afforded the trimer 4 in 97 % yield.…”

“…Recently our group has proposed an alternative synthetic route to prepare C 1 ‐symmetrical CTVs [35] . Using this methodology, we describe in this article the synthesis of a new C 1 ‐symmetrical CTV containing a nitrogen atom in place of one of methylene bridges (CTV‐1 N).…”

Synthesis of Cryptophanes: Recent Advances

“…Deprotection followed by cyclization in HClO 4 resulted in the formation of intermediate 92 , a C 1 ‐symmetrical CTB‐1 N in 60 % overall yield in six linear steps from 2‐amino‐5‐methoxybenzoic acid. The bromo‐compound 90 for BHA was prepared by Barluenga Boronic Coupling (BBA) [63] . X‐ray crystallography confirmed the saddle conformation of CTB‐1 N 92 .…”

Synthesis and Physicochemical Properties of Cryptophazane—A Soluble and Functionalizable C1‐Symmetrical Cryptophane

“…Recently our group has proposed an alternative synthetic route to prepare C 1 -symmetrical CTVs. [35] Using this methodology, we describe in this article the synthesis of a new C 1 -symmetrical CTV containing a nitrogen atom in place of one of methylene bridges (CTV-1 N). Examples of CTVs with modified methylene bridges are rare, [36][37][38][39] and none of these compounds have been used to prepare cryptophanes due to inappropriate structures and/or conformations.…”