Selenoxanthones via directed metalations in 2-arylselenobenzamide derivatives.
The reaction of N, N-diethyl 4-(N', N'-dimethylamino)-2-phenylselenobenzamide (7a), N, N-diethyl 4-methoxy-2-phenylselenobenzamide (7b), N, N-diethyl 4-(N', N'-dimethylamino)-2-[(3-(N, N-dimethylamino)phenylseleno]benzamide (7c), and N, N-diethyl 4-methoxy-2-(3-methoxyphenylseleno)-benzamide (7d) with excess lithium diisopropylamide (LDA) gave 2-N, N-(dimethylamino)-9H-selenoxanthone (9a), 2-methoxy-9H-selenoxanthone (9b), 2,7-bis-N, N-(dimethylamino)-9H-selenoxanthone (9c), and 2,5-dimethoxy-9H-selenoxanthone (9d) in 70%, 59%, 23%, and 90% isolated yields, respectively. N, N-Diethyl 2-phenylselenobenzamide (2-Se) gave no reaction with LDA, t-BuLi, MeLi, or lithium 2,2,6,6-tetramethylpiperidide as base. Electron donation from the 4-substituent of benzamide derivatives 7a-7d may increase the directing ability of the carbonyl oxygen to metalate the 2-position of the arylseleno group.
Brennan
Nancy K
NK
Department of Chemistry, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA.
Donnelly
David J
DJ
Detty
Michael R
MR
D001549:Benzamides / Q000737:chemistry*; D002384:Catalysis; D007202:Indicators and Reagents; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D012235:Rhodamines / Q000737:chemistry; D012643:Selenium / Q000737:chemistry*; D044004:Xanthones / Q000737:chemistry*
D001549:Benzamides; D007202:Indicators and Reagents; D009942:Organometallic Compounds; D012235:Rhodamines; D044004:Xanthones; D012643:Selenium