Site-selective hexa-hetero-functionalization of α-cyclodextrin an archetypical C₆-symmetric concave cycle.

Bo Wang,Maxime Guitet,Elena Zaborova,Yongmin Zhang,Yves Blériot,Mickaël Ménand,Matthieu Sollogoub,Samuel Guieu,Marta Petrillo

doi:10.1038/ncomms6354

Abstract

Access to Cn (n>4) symmetric cyclic concave molecules with a different function on each of their n subunits is an unmet challenge. The reason lies in the lack of a post-functionalization method whose site selectivity is sufficiently understood, predictable and modulable to access most functionalization patterns. Here we disclose a new site-directing rule for a debenzylation reaction on cyclodextrins that solves this problem and allows the unprecedented access to penta- and ultimately hexa-differentiations of such C6 concave cycles. This achievement opens the access to objects with very high-density information.

Highlights

Access to Cn (n44) symmetric cyclic concave molecules with a different function on each of their n subunits is an unmet challenge
The understanding and mastering of the rules of what could be once called a handcraft allowed its conversion into an art, the ‘art of total synthesis’ with so impressive achievements that they can be pointed out as master-pieces[1]
In the differentiated (2 different colours) section, we drew one blue ball plus five white ones, but not the one with five blue balls and one white, which is equivalent in terms of patterns, but which constitutes a totally different species if one thinks of a molecule with two different functions

Summary

12 Arrangements

The case of an important family of compounds: the cyclic concave molecules, which are at the root of supramolecular host-guest chemistry and find applications in daily life and industry These include naturally occurring cyclodextrins (CDs), and synthetic compounds such as calixarenes, cucurbituryls, resorcinarenes, pillararenes, bambusurils, asararenes and so on. Tetradifferentiation has been achieved using the last two methods[39,43,44] This quick survey clearly shows a void in the literature: a method whose site directing effects are sufficiently understood, predictable and modulable to access most functionalization patterns, the ultimate challenge being the access to a hexadifferentiated C6 concave cycle, a task out of sight with current available methodologies. We disclose a new site-directing rule for the debenzylation reaction on CDs that allows the unprecedented construction of penta- and hexadifferentiated concave cycles This achievement opens avenues to objects with very high-density information

Results

DIBAL-H

Discussion

Methods