Improved enamine-type addition of dehydroaporphine using microwave irradiation

✍ Scribed by Wei-Jan Huang; Chih-Chiang Huang; Ling-Wei Hsin; Yeun-Min Tsai; Chin-Ting Lin; Jung-Hsin Lin; Shoei-Sheng Lee

• Book ID: 104097700
• Publisher: Elsevier Science
• Year: 2010
• Tongue: French
• Weight: 402 KB
• Volume: 51
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/j.tetlet.2010.04.008

✦ Synopsis

Previous report demonstrated that 7-substituted aporphine, possessing interesting biological aspects, could be synthesized via an enamine-type addition of dehydroaporphine reacted with an electrophile, but it has the drawbacks of a long reaction time, low yield, and limitation to reactive electrophiles. Here we found that the reaction time and yield could greatly be improved under microwave irradiation in the presence of 4 equiv of sodium iodide for the synthesis of 7-benzyl dehydroglaucine. The application of this finding for treating dehydroglaucine with a variety of alkyl bromides also gave corresponding 7substituted dehydroglaucines (2a-j) with yields of 14-89%. Other enamines such as 1,10-dimethoxydehydroaporphine (3a), 2,9-diacetyldehydroboldine (3b), and 7,8-dihydroberberine (5) were found to react with benzyl bromide under similar conditions as described above to give corresponding products (4a-b, 6) in satisfactory yields, indicating the versatility of this improved reaction condition.