Further Investigations into the Regioselectivity of 6,7-Indole Aryne Cycloadditions with 2-Substituted Furans: Remarkable Contrasteric Preference Depends on Pyrrole and Benzene Ring Substitution
| Autor: | Lincoln Maina, Keith R. Buszek, Neil Brown, Nalin Chandrasoma, Diheng Luo, Alok Nerurkar, Allen Brassfield |
|---|---|
| Rok vydání: | 2013 |
| Předmět: | |
| Zdroj: | Synthesis. 45:1843-1852 |
| ISSN: | 1437-210X 0039-7881 |
| DOI: | 10.1055/s-0033-1338911 |
| Popis: | A series of related 6,7-dibromoindole compounds were prepared to study the effects of pyrrole and benzene ring substitution patterns on the regioselectivity of 6,7-indole aryne cycloadditions with 2-tert-butylfuran. The arynes were generated by our metal–halogen exchange/elimination protocol. The results of this investigation reveal that substitution at the 3-position on the indole ring in particular results in remarkable regiocontrol that favored the contrasteric products. Aromatic conjugation at this site significantly enhanced this effect. However, the presence of most 4- or 5-substituents generally resulted in markedly reduced selectivity. Exceptions in this latter series included the 4-ethyl and 4-iodo cases both of which also gave predominantly contrasteric products even in the absence of a beneficial C-3 substituent. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|