Journal of Organic Chemistry p. 264 - 267 (1991)
Update date:2022-08-03
Topics:
Lai, Yee-Hing
Tan, Chin-Wee
A general approach which involved first the introduction of the central oxy or dioxy bridge and subsequent intramolecular coupling reactions to form the two thia bridges was employed in the syntheses of the 1,2,3-triply bridged cyclophanes 2,3, and 4.The attempted routes to potential precursors of 2 were unsuccessful while the tetrabromide 16 could be synthesized.Intramolecular cyclizations of the latter, however, failed to yield 4, possibly due to the unfavorable stereochemistry of the intermediate leading to the second intramolecular coupling reaction.The tetrabromide 18, with a central bridge of an appropriate length, successfully led to the formation of 3.The conformational behavior of 3 was analyzed by dynamic 1H NMR spectroscopy.The ethylenedioxy bridge is believed to adopt the symmetrical "boat" conformation.All three bridges, however, undergo unrestricted pseudorotation, represented by free conformational interconversion 3b <--> 3c, at room temperature.A relatively frozen conformation 3b(3c) was observed at the low-temperature limit.Flipping processes of the ethylenedioxy bridge and the two thia bridges are found to be interdependent, resulting in an propelling process with a common conformational barrier estimated at ca. 45 kJ mol-1.
View Morewebsite:http://www.debyesci.com
Contact:+85221376140
Address:Rm. 19C, Lockhart Ctr., 301-307 Lockhart Rd., Wan Chai
zhengzhou Triz Pharma-Tech Co., Ltd
website:http://www.Trizpharma-tech.com
Contact:+86-0371-86597269,53392065
Address:High-tech Industrial Development Zone, Zhengzhou City, NO.7 Holly Street
Contact:86 513 85512619
Address:Rm.1306, Building A, Wenfeng Mansion,168 Gongnong Road, Nantong Jiangsu China
website:http://www.gihichemicals.com
Contact:+86-571-86217390
Address:No.567 Dengcai Street,Sandun,Westlake District,Hangzhou310030,Zhejiang,China.
NANCHANG QINZHI SCI&TEC.CO.,LTD
Contact:+86-13687004106
Address:Hero South Road,Hero Zone,Nanchang,Jiangxi,China
Doi:10.1248/cpb.30.484
(1982)Doi:10.1021/ja046241e
(2004)Doi:10.1007/BF00526078
(1982)Doi:10.1021/jo00144a011
(1982)Doi:10.1021/jm030638w
(2004)Doi:10.1016/S0040-4020(01)88686-5
(1983)