Synthetic and theoretical aspects of new dimroth rearrangement of 6-aminopyran-2-ones to 6-hydroxypyridin-2-ones via carbamoyl ketenes / Subbotina JO,Fabian WMF,Tarasov EV,Volkova NN,Bakulev VA // EUROPEAN JOURNAL OF ORGANIC CHEMISTRY. - 2005. - V. , l. 14. - P. 2914-2923.

ISSN/EISSN:

1434-193X / нет данных

Type:

Article

Abstract:

Two alternative directions for thermal transformation of 6-amino-4-oxopyrano{[}3,4-d] {[}1,2,3]thiadiazoles 1, leading either to 6-hydroxy-4-oxo-{[}1,2,3]thiadiazolo{[}4,5-c]pyridines 2 or 2-cyano-2-(1,2,3-thiadiazol-5-yl)acetamide 4b, were observed. The first one represents a new, Dimroth-type rearrangement and proceeds by thermal opening of the pyrane ring, followed by the simultaneous rotational isomerization of the ketene intermediate 7 (s-cis) to 7 (s-trans) and its recyclization onto the amido group to form the pyridin-2-one cycle. The first step of the rearrangement has a calculated {[}B3LYP/6-31G(d)] activation barrier of 24-34 kcal/mol, the involvement of amines reduces it by ca. 5 kcal/mol {[}PCM-B3LYP/6-31G(d), DMSO]. In contrast, the recyclization step onto the amido group is calculated to occur essentially barrierless (Delta E < 2 kcal/mol). The influence of substituents, in particular of those capable of intramolecular hydrogen bonding, on the preferred reaction path was also studied. The alternative ring opening of the pyrane cycle was calculated to be at least 5 kcal/mol {[}B3LYP/6-31G(d)] less favorable than the Dimroth rearrangement. ((c) Wiley-VCH Verlag GmbH \& Co. KGaA, 69451 Weinheim, Germany, 2005)

Author keywords:

rearrangement; reaction mechanisms; hydrogen bond; ketene intermediates; DFT calculations POLARIZABLE CONTINUUM MODEL; AB-INITIO; ALPHA-PYRONE; HYDROGEN-BONDS; PSEUDOPERICYCLIC REACTIONS; PROTON-TRANSFER; GAS-PHASE; REACTIVITY; DENSITY; ISOMERIZATION

DOI:

нет данных

Web of Science ID:

ISI:000230536400007

Соавторы в МНС:

—

Другие поля

Поле	Значение
Month	JUL 11
Publisher	WILEY-V C H VERLAG GMBH
Address	PO BOX 10 11 61, D-69451 WEINHEIM, GERMANY
Language	English
Keywords-Plus	POLARIZABLE CONTINUUM MODEL; AB-INITIO; ALPHA-PYRONE; HYDROGEN-BONDS; PSEUDOPERICYCLIC REACTIONS; PROTON-TRANSFER; GAS-PHASE; REACTIVITY; DENSITY; ISOMERIZATION
Research-Areas	Chemistry
Web-of-Science-Categories	Chemistry, Organic
Author-Email	walter.fabian@uni-graz.at vab@htf.ustu.ru
ResearcherID-Numbers	Subbotina, Julia/L-7131-2016
ORCID-Numbers	Subbotina, Julia/0000-0002-2227-0787
Number-of-Cited-References	57
Usage-Count-Last-180-days	1
Usage-Count-Since-2013	4
Journal-ISO	Eur. J. Org. Chem.
Doc-Delivery-Number	945XN