close

Вход

Забыли?

вход по аккаунту

?

код для вставки
200517.fm Page 194 Friday, March 18, 2005 2:52 PM
2005
Multi-membered O,S-heterocycles
R 0691
Tandem Intramolecular Nicholas and Pauson—Khand Reactions for the Syntheof Tricyclic Oxygen-Containing Heterocycles. — Simple acyclic enynes (I) are
17- 175 sis
converted into tricyclic ethers (V)/(VI) via cobalt carbonyl complexes (III) which
undergo Nicholas reaction to furnish cobalt-complexed cyclic alkyne ethers (IV). The
following Pauson—Khand reaction to provide the target tricycles proceeds with good
to excellent yields under a variety of conditions for the [5,7,5]- and [5,8,5]-tricyclic
ethers. In contrast, both the Nicholas reaction to yield cyclic ether (IVa) and the
Pauson—Khand reaction to provide the [5,6,5]-tricycle are very inefficient. An attempted Nicholas reaction of enyne complex (VII) to obtain finally a [6,8,5]-tricyclic
analogue of compounds (V)/(V) fails. — (QUINTAL, M. M.; CLOSSER, K. D.;
SHEA*, K. M.; Org. Lett. 6 (2004) 26, 4949-4952; Dep. Chem., Smith Coll.,
Northampton, MA 01063, USA; Eng.) — Klein
Документ
Категория
Без категории
Просмотров
0
Размер файла
32 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа