Browsing by Author "Ho, TL"

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A concise route to racemic anatoxin a from cycloocta-1,5-diene
(2006)
Ho, TL
;
Zinurova, E
;
應用化學系
;
Department of Applied Chemistry
The synthesis of racemic anatoxin a (1a) from cycloocta-1,5-diene via its 1:1 cycloadduct with N-chlorosulfonyl isocyanate is described. The N-unsubstituted beta-lactam 2b was converted to a beta-amino ester 3 which was then submitted to a Pd-catalyzed cyclization to afford the conjugated ester 4a. The N-tosyl derivative 4b was then elaborated into N-tosylanatoxin a (1b) via a Weinreb amide.
A new approach to nicotine: Symmetry consideration for synthesis design
(2004)
Ho, TL
;
Kuzakov, EV
;
應用化學系
;
Department of Applied Chemistry
A synthesis of nicotyrine (9), and hence formally racemic nicotine, was carried out by elaboration of the 1:1 adduct 2 of cycloocta-1,5-diene and chlorosulfonyl isocyanate (ClSO2-NCO). Transformation of adduct 2 into carbamate 4 was followed by ozonolysis, tosylation, and NaH treatment, which led to pyrrolidinylpiperidinone 6. LiAlH4 Reduction, debenzylation, and aromatization yielded 2.
A stereoselective synthesis of platyphyllide
(1999-07-07)
Ho, TL
;
Ho, MF
;
應用化學系
;
Department of Applied Chemistry
The norsesquiterpene lactone, platyphyllide has been synthesized in 8 steps in 23% overall yield via the Diels-Alder adduct of 2-(4-methylpent-3-enyl)furan with dimethyl acetylenedicarboxylate, the 3-substituted phthalic diester, and an o-formylbenzamide. An intramolecular ene reaction established the skeleton, and the final step involved inversion of configuration at the benzylic site.
A synthesis of 6-myoporol
(1997-05-01)
Ho, TL
;
Chein, RJ
;
交大名義發表
;
應用化學系
;
National Chiao Tung University
An approach to (+/-)-6-myoporol (1) featured stereocontrol by equilibration of 2,6-disubstituted cyclohexanones to mainly the cis isomer. The synthesis was completed by reaction of a lactone intermediate with 3-lithiofuran, Mitsunobu reaction, and hydrolysis.
A synthesis of 6-myoporol
(1997-05-01)
Ho, TL
;
Chein, RJ
;
應用化學系
;
Department of Applied Chemistry
An approach to (+/-)-6-myoporol (1) featured stereocontrol by equilibration of 2,6-disubstituted cyclohexanones to mainly the cis isomer. The synthesis was completed by reaction of a lactone intermediate with 3-lithiofuran, Mitsunobu reaction, and hydrolysis.
A synthesis of alpha-cuparenone based on symmetry considerations
(1997-06-01)
Ho, TL
;
Chang, MH
;
交大名義發表
;
應用化學系
;
National Chiao Tung University
A ring expansion approach to alpha-cuparenone was accomplished in 5 or 6 steps. The key intermediate is 3-methyl-3-(4-methylphenyl)cyclobutanone, which was derived from a [2+2]cycloaddition of dichloroketene on a styrene derivative, followed by dechlorination.
A synthesis of alpha-cuparenone based on symmetry considerations
(1997-06-01)
Ho, TL
;
Chang, MH
;
應用化學系
;
Department of Applied Chemistry
A ring expansion approach to alpha-cuparenone was accomplished in 5 or 6 steps. The key intermediate is 3-methyl-3-(4-methylphenyl)cyclobutanone, which was derived from a [2+2]cycloaddition of dichloroketene on a styrene derivative, followed by dechlorination.
A synthetic approach to tacamonine. Access to 3-epitacamonine and 14-epitacamonine
(2001-01-14)
Ho, TL
;
Su, CY
;
應用化學系
;
Department of Applied Chemistry
3-Epitacamonine and 14-epitacamonine have been synthesized starting from the dinitrile 3. The synthetic route was designed on the basis of symmetric considerations which emphasized the establishment of the relative configuration in two of the three stereocenters. (C) 2001 Elsevier Science Ltd. All rights reserved.
A synthetic approach to the secoswartzianins.
(1998-04-02)
Ho, TL
;
Chang, JW
;
應用化學系
;
Department of Applied Chemistry
Abnormal and regioselective Wacker oxidation of 1,5-dienes
(2003-09-01)
Ho, TL
;
Chang, MH
;
Chen, C
;
應用化學系
;
Department of Applied Chemistry
The presence of an additional double bond can change the regioselectivity of the Wacker oxidation of a 1-alkene moiety to give the aldehyde product. (C) 2003 Published by Elsevier Ltd.
Approaches to tacamonine.
(2001-04-01)
Ho, TL
;
Su, CY
;
Gorobets, E
;
應用化學系
;
Department of Applied Chemistry
Convenient synthesis of tavacpallescensin and occidol.
(1997-04-13)
Ho, TL
;
Lin, YJ
;
應用化學系
;
Department of Applied Chemistry
Desilylative oxidation of alkyl trimethylsilyl ethers with pyridinium fluorochromate
(1999-08-01)
Ho, TL
;
Jana, GH
;
應用化學系
;
Department of Applied Chemistry
Direct conversion of alkyl trimethylsilyl ethers to carbonyl compounds is accomplished using PFC in dichloromethane at room temperature. For a similar oxidation of t-butyldimethylsilyl ethers the PCC-n-Bu4NF combination may be employed.
Formal synthesis of vallesamidine
(2006)
Ho, TL
;
Chen, CK
;
應用化學系
;
Department of Applied Chemistry
A novel route to the racemic selenide (1RS, 12bRS)-1-ethyl -2,3,6,7,12,12b-hexahydro-1- [2(phenylseleno)ethyl]indolo[2,3-a]quinolizin-4(1H)-one (13b), a key intermediate in the total synthesis of vallesamidine (1), was elaborated. Compound 3a, obtained by Pictet-Spengler reaction of tryptamine and cyclohept-4-enyl-1-carbaldehyde (2c), was oxidized with KMnO4 to the diacid 4, which was subsequently converted into the isomeric tetracyclic lactams 5a,b. After proper protection maneuvers, Barton decarboxylation of 10a,b, trapping with PhSe2Ph, and Boc removal afforded 13b.
Generation of 9(10H)-acridone from anthranilic acid
(2001-02-01)
Ho, TL
;
Jou, DG
;
應用化學系
;
Department of Applied Chemistry
Diazotization of anthranilic acid with butyl nitrite in refluxing THF gave rise to acridone.
Intervention of phenonium ion in Ritter reactions
(2004-01-23)
Ho, TL
;
Chein, RJ
;
應用化學系
;
Department of Applied Chemistry
The transformation of phenylethyl chloride to 3,4-dihydroisoquinolines is shown to proceed via phenonium ion. The evidence comes from a study of dideuterated analogue 4, and the monomethylated and dimethylated compounds 2 and 3.
Ionization of 2-halo-1,1-difluoro-1-arylethanes in the presence of nitriles.
(2004-08-22)
Ho, TL
;
Chein, RJ
;
應用化學系
;
Department of Applied Chemistry
New synthesis of tacamonine.
(2003-09-01)
Ho, TL
;
Chung, WC
;
應用化學系
;
Department of Applied Chemistry
Ritter reaction of 1-aryl-1-fluoro-2-haloethanes
(2006-04-01)
Ho, TL
;
Chein, RJ
;
應用化學系
;
Department of Applied Chemistry
Fluorinated phenethyl bromides 1, 2, and 3, prove to be totally inert under Ritter reaction conditions in the presence of either SnCl4 or AgNO3, due to the strong deactivation by the gem-difluoro unit. Subjecting 2-bromo-1-fluoro-1-phenylethane to SnCl4 in MeCN at elevated temperatures led to formation of 2-methyl-4-phenyl-4,5-dihydrooxazole.
Stereoselective synthesis of 2-isocyanoallopupukeanane
(1999-10-07)
Ho, TL
;
Kung, LR
;
應用化學系
;
Department of Applied Chemistry
[GRAPHICS] A stereoselective synthesis of 2-isocyanoaliopupukeanane (3) in ca, 5% overall yield features an intramolecular Diels-Alder reaction to establish a bridged cydopentane ring to the existing bicyclo[3.2.1]octane unit.