Poster (Scientific congresses and symposiums)
Novel strategy towards oxazine free amines from a novel class of photocleavable acyl nitroso featuring key photochemical steps under continuous flow conditions.
Toupy, Thomas; Tilmant, Thomas; Monbaliu, Jean-Christophe
20197th Conference on Frontiers in Organic Synthesis Technology (FROST 7)
 

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Keywords :
Hydroxycarbamate; Oxazine; Acyl Nitroso; Microfluidic; Continuous Flow; Photochemistry
Abstract :
[en] Throughout this research program the preparation of (bicyclo)-3,6-dihydro-1,2- oxazines bearing a free amine was studied. The developed synthetic strategy relies on the unprecedented nitroso hetero Diels-Alder (nHDA) reaction between (non)- cyclic dienes and a photolabile acyl nitroso species which acts as a highly reactive dienophile. The developed strategy is composed of 4 chemical steps.In the first step, the preparation of a chloroformate intermediate is conducted by reacting the alcohol derivative of the nitropiperonal moiety (which is a known photolabile protecting group) with a phosgene analogous. The second step relies on the preparation of the key hydroxycarbamate intermediate by reacting the chloroformate species with hydroxylamine hydrochloride. The third step is the in situ oxidation reaction of the key hydroxycarbamate intermediate into the desired acyl nitroso species which will act as a highly reactive dienophile with (non)-cyclic dienes. A photochemical alternative under continuous flow operation is also envisioned. Upon reaction, the cycloadduct can be photocleaved under microfluidic conditions in the last step to yield the desired oxazine moiety bearing a free amine. The designed strategy proved to be robust and efficient upon preparation of a library of cycloadducts with various non-cyclic dienes such as 2,3-dimethyl-1,3-butadiene or cyclic dienes of varying ring sizes ranging from cyclopentadiene to cyclooctadiene. Non-symmetrical dienes were also investigated such as the terpinene derivatives. Using our designed acyl nitroso species, we observed a significant regioselectivity in the case of non-symmetrical dienes. Finally, successful photocleavage of the nitropiperonal moiety was conducted upon irradiation of the cycloadduct under microfluidic conditions yielding the desired oxazine bearing a free amine.
Research center :
Center for Integrated Technology and Organic Synthesis (CiTOS)
Disciplines :
Chemistry
Author, co-author :
Toupy, Thomas ;  Université de Liège - ULiège > Département de chimie (sciences) > CITOS
Tilmant, Thomas ;  Université de Liège - ULiège > Département de chimie (sciences) > Département de chimie (sciences)
Monbaliu, Jean-Christophe  ;  Université de Liège - ULiège > Département de chimie (sciences) > Synthèse organique appliquée
Language :
English
Title :
Novel strategy towards oxazine free amines from a novel class of photocleavable acyl nitroso featuring key photochemical steps under continuous flow conditions.
Publication date :
17 October 2019
Number of pages :
A0
Event name :
7th Conference on Frontiers in Organic Synthesis Technology (FROST 7)
Event organizer :
Flow Chemistry Society
Event place :
Budapest, Hungary
Event date :
du 16 octobre 2019 au 18 octobre 2019
Audience :
International
Available on ORBi :
since 10 December 2019

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