New chiral acids for catalysis – NeoACat
The acceleration of the chemical reactions involved in the present project was achieved by investigating small molecules that interacted efficiently with the various partners of the reaction. The objective was to promote mildest as possible chemical transformations to avoid the recourse to extreme temperature and excessive chemical wastes generation. During this project, innovative and original synthetic methodologies associated to catalyst’s original design led to relevant results. The use of metal-free molecules (to avoid metal toxicity and negative impact on the environment) was determining. As a consequence the main elements used for the catalyst design were carbon, oxygen, sulphur and bore.
The synthesis of various racemic sulfonic acids has been achieved.
However, technical issues during the separation of enantiomers led to revisit the initial obectives.
Accordingly the development of relevant new boron-derived acids for the mild synthesis of amides was investigated. Initial related resulst allowed to publish in Chemistry - A European Journal
The evaluation and optimization of new boron-derived acids for the mild synthesis of amides will be continued to fulfill the actual demand in term of reactivity and reaction scope.
Finally the problems encountered when dealing with the initial objective will be reassed and alternatives will be proposed and studied.
1 publication
1. An Easy Route to (Hetero)arylboronic Acids.
Erb, W.; Hellal, A.; Albini, M.; Rouden, J.; Blanchet, J. Chem. Eur. J. 2014, DOI: 10.1002/chem.201402487
The aim of this program is the development of several new class of chiral acid catalyst. The desired structures are based on sulfonic acids involving C2 asymmetrical elements (pentasubstituted benzene sulfonic acids derivatives). The preparation of those acids is expected to be facilitated by preliminary unpublished results obtained in our laboratory and should lead to a versatile synthesis of this original class of molecules. Furthermore, progress regarding the synthetic plan would improve dramatically the easiness of the modulation of the stereo-electronic properties of the targeted acids.
Thus our first goal would be to capitalize our accumulated knowledge and create a small library of those catalysts. In a second part those catalysts will be tested in a series of reaction where traditionally chiral phosphoric acids derived from BINOL are known to behave sluggishly, according to their intrinsic limited acidity (Mannich and aldol reactions, resolution of alcohol through a stereoablative elimination reaction, protonation of hindered silyl ketene acetals). In a final and third part, innovative way to create asymmetry will be evaluated based on the unique opportunity offered by the original scaffold developed in the program. Various conceptually new chiral silyl Lewis acids will be prepared and tested in important transformations (Diels Alder, Mukaiyama aldol).
Project coordination
Jérôme Blanchet (Laboratoire de Chimie Moléculaire et Thioorganique) – jerome.blanchet@ensicaen.fr
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
Partner
UMR 6507 CNRS Laboratoire de Chimie Moléculaire et Thioorganique
Help of the ANR 155,725 euros
Beginning and duration of the scientific project:
January 2013
- 36 Months
