Showing papers by "Tomas Hudlicky published in 2003"
TL;DR: 1-chloro-(2S, 3S)-dihydroxycyclohexa-4,6-diene as discussed by the authors, 4,6 -diene.
Abstract: 1-chloro-(2S,3S)-dihydroxycyclohexa-4,6-diene
product: 1-chloro-(2S,3S)-dihydroxycyclohexa-4,6-diene
Keywords:
addition, to CC;
enzymatic reactions;
hydroxylation
27 citations
TL;DR: In this article, a deprotection of the cinnamyl moiety from ethers, esters, and carbamates was studied with the focus on O- versus N- selectivity as well as selectivity over allyl or benzyl systems.
17 citations
TL;DR: In this article, the authors discuss the logic of general synthetic design for lycoricidine, narciclasine, pancratistatin, and 7-deoxypancratistsatin.
Abstract: Biocatalytic approaches have yielded efficient total syntheses of the major Amaryllidaceae alkaloids, all based on the key enzymatic dioxygenation of suitable aromatic precursors. This paper discusses the logic of general synthetic design for lycoricidine, narciclasine, pancratistatin, and 7-deoxypancratistatin. Experimental details are provided for the recently accomplished syntheses of narciclasine, ent-7-deoxypancratistatin, and 10b-epi-deoxypancratistatin via a new and selective opening of a cyclic sulfate over aziridines followed by aza-Payne rearrangement. The structural core of 7-deoxypancratistatin has also been degraded to a series of intermediates in which the amino inositol unit is cleaved and deoxygenated in a homologous fashion. These truncated derivatives and the compounds from the synthesis of the unnatural derivatives have been tested against six important human cancer cell lines in an effort to further develop the understanding of the mode of action for the most active congener in this group, pancratistatin. The results of the biological activity testing as well as experimental, spectral, and analytical data are provided in this manuscript for all relevant compounds.
5 citations
TL;DR: The Burgess reagent has been used primarily for the dehy-dration of secondary and tertiary alcohols, and its use has figured in the total synthesis of important natural prod- ucts, for example in Rigby's syntheses of narciclasine 3 and cedrene, 4 Nicolaou's synthesis of efrotomycin, 5 Uskokovic's synthesis, 6 and Holton's syn- thesis of Taxol ® as discussed by the authors.
Abstract: Burgess reagent, (methoxycarbonylsulfamoyl)triethyl- ammonium hydroxide, usually used for the dehydration of second- ary or tertiary alcohols, was successfully employed in the formation of sulfamidates from the corresponding epoxides. It was further shown that the same reaction with aromatic epoxides results in the formation of seven-membered ring systems. In 1970 Burgess and coworkers described a new and very mild method for the dehydration of secondary and tertiary alcohols to the corresponding olefins using the inner salt of (methoxycarbonylsulfamoyl)triethylammonium hy- droxide (2, Burgess reagent). 1 The proposed mechanism involves the attack of the hydroxyl functionality onto the sulfur followed by syn-elimination of the intermediate sulfamate (3), Scheme 1. The Burgess reagent has been used primarily for the dehy- dration of secondary and tertiary alcohols, 2 and its use has figured in the total synthesis of important natural prod- ucts, for example in Rigby's syntheses of narciclasine 3 and cedrene, 4 Nicolaou's synthesis of efrotomycin, 5 Uskokovic's synthesis of pravastatin, 6 and Holton's syn- thesis of Taxol ® . 7 Further applications have been report- ed, for example nitrile formation from primary amides, 8 isocyanide formation from formamides, 9 and synthesis of urethanes from primary alcohols. 1,10 Wipf developed a
3 citations
TL;DR: In this article, a 4.4-dimethyl-2-cyclopenten-1-one (4.4dimethyl2-4-oxopentanal) was used.
Abstract: 4,4-Dimethyl-2-cyclopenten-1-one
intermediate: 165.1 g (1.29 mol) 2,2-dimethyl-4-oxopentanal
product: 4,4-dimethyl-2-cyclopenten-1-one
Keywords:
annulation, carbocyclic-[5];
cyclization, condensation;
metal-catalyzed reactions, palladium;
oxidation, CHCH2 COCH3
2 citations
TL;DR: In this article, a deprotection of the cinnamyl moiety from ethers, esters, and carbamates was studied with the focus on O- versus N- selectivity as well as selectivity over allyl or benzyl systems.
Abstract: Electrochemical deprotection of the cinnamyl moiety from ethers, esters, and carbamates was studied with the focus on O- versus N- selectivity as well as selectivity over allyl or benzyl systems.
1 citations
TL;DR: The Burgess reagent has been used primarily for the dehy-dration of secondary and tertiary alcohols, and its use has figured in the total synthesis of important natural prod- ucts, for example in Rigby's syntheses of narciclasine 3 and cedrene, 4 Nicolaou's synthesis of efrotomycin, 5 Uskokovic's synthesis, 6 and Holton's syn- thesis of Taxol ® as mentioned in this paper.
Abstract: Burgess reagent, (methoxycarbonylsulfamoyl)triethyl- ammonium hydroxide, usually used for the dehydration of second- ary or tertiary alcohols, was successfully employed in the formation of sulfamidates from the corresponding epoxides. It was further shown that the same reaction with aromatic epoxides results in the formation of seven-membered ring systems. In 1970 Burgess and coworkers described a new and very mild method for the dehydration of secondary and tertiary alcohols to the corresponding olefins using the inner salt of (methoxycarbonylsulfamoyl)triethylammonium hy- droxide (2, Burgess reagent). 1 The proposed mechanism involves the attack of the hydroxyl functionality onto the sulfur followed by syn-elimination of the intermediate sulfamate (3), Scheme 1. The Burgess reagent has been used primarily for the dehy- dration of secondary and tertiary alcohols, 2 and its use has figured in the total synthesis of important natural prod- ucts, for example in Rigby's syntheses of narciclasine 3 and cedrene, 4 Nicolaou's synthesis of efrotomycin, 5 Uskokovic's synthesis of pravastatin, 6 and Holton's syn- thesis of Taxol ® . 7 Further applications have been report- ed, for example nitrile formation from primary amides, 8 isocyanide formation from formamides, 9 and synthesis of urethanes from primary alcohols. 1,10 Wipf developed a
1 citations
TL;DR: In this article, 3-hydroxy-1-cyclohexene-1-(1,3-Dithian-2-yl)-2-cycloehexen-1.1-carboxaldehyde was used to synthesize thioacetal formation.
Abstract: 3-Hydroxy-1-cyclohexene-1-carboxaldehyde
intermediate: 1-(1,3-Dithian-2-yl)-2-cyclohexen-1-ol (2)
product: 3-Hydroxy-1-cyclohexene-1-carboxaldehyde (3)
Keywords:
acetal (and thioacetal) formation;
addition, to CO;
hydrolysis, acetals and ketals;
rearrangements;
ring opening reactions;
boron trifluoride etherate;
tetrahydrofuran;
benzene