The Life and Thought of Yeh Shih. By Winston Wan Lo. Hong Kong: The Chinese University of Hong Kong and the University Presses of Florida, 1974. 206 pp. Index, Glossary. $10.00

1976 ◽  
Vol 36 (1) ◽  
pp. 126-127
Author(s):  
George Hatch
Author(s):  
Douglass F. Taber

Richard J. K. Taylor of the University of York employed (Tetrahedron Lett. 2011, 52, 2024) the Jørgensen protocol to add 2 to 1, to give the enantiomerically enriched cyclohexenone 3. Condensation of 3 with aqueous ammonia led directly to (-)-mearsine 4. Wei-Dong Z. Li of Nankai University found (Org. Lett. 2011, 13, 3538) that the intermediate from Dibal reduction of the lactone 5 underwent Nazarov cyclization, giving the α-hydroxy cyclopentenone 6. After acetylation, deprotection gave an amine that cyclized with high diastereocontrol, leading to (±)-cephalotaxine 7. Tony K. M. Shing of the Chinese University of Hong Kong cyclized (Org. Lett. 2011, 13, 2916) the aldehyde 8 by exposure to 9. The product 10 was carried on to (-)-cocaine 11, as well as several hydroxylated cocaine derivatives. Susumi Hatakeyama of Nagasaki University found (Tetrahedron Lett. 2011, 52, 923) that exposure of the simple prochiral aldehyde 12 to catalytic proline transformed it, after reduction, into the cyclized diol 13 in high ee. The diol 13 was readily carried on to quinine 14. M.-Lluïsa Bennasar of the University of Barcelona devised (Org. Lett. 2011, 13, 2042) Pd-catalyzed conditions for the cyclization of 15 that selectively delivered the unstable kinetic product 18. Selective hydrogenation of the more reactive bridgehead alkene then led to cleavamine 17. The alkene 16 is also prochiral, so it is possible that a catalyst could be found that would deliver 17 in high ee. The synthesis of the heptacyclic alkaloid strychnine 23 would, in the past, have been a major undertaking. Christopher D. Vanderwal of the University of California, Irvine, prepared (Chem. Sci. 2011, 2, 649) 23 in just six linear steps. The dienyl aldehyde 18 was available in two steps from tryptophyl bromide. Exposure to t -BuOK cyclized 18 to 19. N-deallylation followed by alkylation with 20 provided 21, setting the stage for a truly spectacular Brook rearrangement/conjugate addition, to give the Wieland-Gumlich aldehyde 22. The known condensation with malonic acid completed the preparation of 23.


1989 ◽  
Vol 13 (2) ◽  
pp. 67-69 ◽  
Author(s):  
C. K. Wong

There are two medical schools in Hong Kong, that of the University of Hong Kong and that of the Chinese University of Hong Kong. The former has a history of more than 100 years whereas the latter admitted its first batch of students only in 1981. Both use English as the teaching medium and both are recognised by the GMC. I received my undergraduate medical education in the former but have been teaching in the latter for seven years.


Author(s):  
Douglass F. Taber

It has generally been observed that prospective intramolecular Diels-Alder cycloadditions that would form a γ-lactone are reluctant to proceed. In the course of a synthesis of (±)-neovibsanin B 4, Hiroshi Imagawa and Mugio Nishizawa of Tokushima Bunri University reversed (Organic Lett. 2009, 11, 1253) the usual connectivity and found that the dienyl ester 1 could be induced to cyclize to 3. The solvent 2 improved both the yield and the diastereoselectivity of the cycloaddition. It was not surprising that Johann Mulzer of the University of Vienna could see (Organic Lett. 2009, 11, 1151) no evidence of cyclization on heating the acrylate 5. In contrast, following the lead of Barriault, they found that MgBr2 -tethered cycloaddition of methyl acrylate 7 with the alcohol 6 proceeded smoothly, to give 8, which they carried on to valerenic acid 9. Intramolecular Diels-Alder reactions to form 6,6-systems are often facile. Mohammad Movassaghi of MIT, en route to (-)-himandrine 12, showed (J. Am. Chem. Soc. 2009, 131, 9648) that the tetraene 10 cyclized to 11 at 95°C with 5:1 dr. In this case the solvent was the more typical acetonitrile with 10% diethyl aniline. The intramolecular Diels-Alder reaction is concerted but nonsynchronous (Tetrahedron Lett. 1981, 22, 5141), with β-bond formation preceding α-bond formation. This contributes to the reluctance of 8 to cyclize. In contrast, Henry N. C. Wong of the Chinese University of Hong Kong observed (Angewandte Chem. Int. Ed. 2009, 48, 2351) that the tetraene 13, which is polarity matched, cyclized to 14 spontaneously as soon as it was formed. Functional group conversion completed the synthesis of (±)-pallavicinolide A 15. The transannular Diels-Alder (TADA) reaction can proceed with high diastereocontrol, but the factors directing these cyclizations are not completely understood. In the course of a synthesis of (+)-phomopsidin 18, Masahisa Nakada of Waseda University found (Tetrahedron 2009, 65, 888) that 16 led to 17 with 16:1 dr. In contrast, the triene epimeric to 16 at the silyloxy group cyclized with only 2:1 dr.


2004 ◽  
Vol 08 (23) ◽  
pp. 1262-1264
Author(s):  
Chun-Tao Che

This article is about the Chinese Medicine Education at the Chinese University of Hong Kong. It discusses the postgraduate programs and the research activities as wellas the sub-degree programs in the University.


Sign in / Sign up

Export Citation Format

Share Document