The Journal of Organic Chemistry
We studied the scope and limitations of a tandem intramolecular Nicholas/Pauson−Khand strategy for the synthesis of tricyclic oxygen- and nitrogen-containing heterocycles. This methodology enables conversion of simple acyclic starting materials into a series of previously unknown heterocyclic architectures. For the preparation of cyclic ethers (Z = O), tricyclic [5,6,5]- through [5,9,5]-systems (m = 1, n = 1−4) are available with the [5,7,5]- and [5,8,5]-systems amenable to quick and efficient synthesis. Tricyclic [5,7,5]- and [5,8,5]-amine-containing (Z = NTs) heterocycles can be successfully prepared. Attempts to make larger ring systems (Z = O, m = 2; Z = O, n = 5; or Z = NTs, n = 4−5) or prepare lactones via Nicholas reactions with carboxylic acid nucleophiles (available via oxidation of alcohol nucleophiles, Z = O) result in decomposition or dimerization. The latter process enables formation of 14-, 16-, and 18-membered ring diolides when using carboxylic acid nucleophiles. We also investigated the use of chiral amine promoters in the Pauson−Khand step but found no asymmetric induction.
“This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of Organic Chemistry, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see [insert ACS Articles on Request author-directed link to Published Work, see http://pubs.acs.org/doi/abs/10.1021/jo8027592
Closser, Kristina D.; Quintal, Miriam M.; and Shea, Kevin M., "The Scope and Limitations of Intramolecular Nicholas and Pauson-Khand Reactions for the Synthesis of Tricyclic Oxygen- and Nitrogen-Containing Heterocycles" (2009). Chemistry: Faculty Publications. 8.