scholarly journals Total Synthesis of 6-Deoxydihydrokalafungin, a Key Biosynthetic Precursor of Actinorhodin, and Its Epimer

Molecules ◽  
2021 ◽  
Vol 26 (21) ◽  
pp. 6397
Author(s):  
Takuya Kumamoto ◽  
Mika Kainuma ◽  
Azusa Takahashi ◽  
Yoshika Matsuo ◽  
Kazuaki Katakawa ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Trans Isomer ◽  
Similar Sequence ◽  
Subsequent Oxidation ◽  
Biosynthetic Precursor ◽  
Cis Isomer

In this article, we report the total synthesis of 6-deoxydihydrokalafungin (DDHK), a key biosynthetic intermediate of a dimeric benzoisochromanequinone antibiotic, actinorhodin (ACT), and its epimer, epi-DDHK. Tricyclic hemiacetal with 3-siloxyethyl group was subjected to Et3SiH reduction to establish the 1,3-cis stereochemistry in the benzoisochromane, and a subsequent oxidation/deprotection sequence then afforded epi-DDHK. A bicyclic acetal was subjected to AlH3 reduction to deliver the desired 1,3-trans isomer in an approximately 3:1 ratio, which was subjected to a similar sequence to that used for the 1,3-cis isomer that successfully afforded DDHK. A semisynthetic approach from (S)-DNPA, an isolable biosynthetic precursor of ACT, was also examined to afford DDHK and its epimer, which are identical to the synthetic products.

scholarly journals Reaction of cis- and trans-Dichlorotetra(Dimethylsulfoxide)Ruthenium(II) With the Antiviral Drug Acyclovir

2000 ◽  
Vol 7 (6) ◽  
pp. 325-334 ◽  
Author(s):  
Aglaia Koutsodimou ◽  
Giovanni Natile
Keyword(s):  
Trans Isomer ◽  
Early Stage ◽  
Antiviral Drug ◽  
Metallic Substrate ◽  
Purine Base ◽  
Coordination Environment ◽  
Molar Ratios ◽  
Discrete Amount ◽  
Cis And Trans ◽  
Cis Isomer

NMR was used to investigate the reaction of cis- and trans-[RuCl2(DMSO)4] with the antiviral drug acyclovir, a guanine derivative containing the acyclic (2-hydroxo) ethoxymethyl pendant linked to N(9). Studies were performed in aqueous solutions at ambient temperature and at 37 °C, and at various molar ratios. Both isomers yielded two compounds, a monoadduct and a bisadduct, the relative yields being dependent upon the metal to ligand concentration ratios. The products derived from the two Ru isomers displayed identical NMR spectra, suggesting that they have the same coordination environment, however the rate of formation of the monoadduct was higher in the case of the trans isomer than in the case of the cis isomer, while the rate of conversion of the monoadduct into the bisadduct appeared to be similar in both cases. As a consequence in the case of the trans isomer there is accumulation of monoadduct in the early stage of the reaction, whose concentration afterwards decreases with the progress of the reaction. As for platinum, also for ruthenium the preferred binding site is N(7) of the purine base, however, in the case of ruthenium a discrete amount of bisadduct is formed even in the presence of an excess of metallic substrate with respect to the acyclovir ligand; under similar conditions a platinum substrate would have given, nearly exclusively, the monoadduct.

Total Synthesis of S-(+)-Argentilactone

2001 ◽  
Vol 56 (3) ◽  
pp. 325-328 ◽  
Author(s):  
Muhammad Saeed ◽  
Muhammad Abbas ◽  
Khalid Mohammad Khan ◽  
Wolfgang Voelter
Keyword(s):  
Total Synthesis ◽  
Wittig Reaction ◽  
Subsequent Oxidation

Abstract Asymmetrie Total Synthesis Asymmetrie total synthesis of S-(+)-argentilactone (2) was accomplished, using methyl-a-D-glucopyranoside (3) as carbohydrate template. Benzylidene acetal 5 was hydrolysed with tBuOOH/AlCl3 and further manipulated to produce the aldehyde 10. A Wittig reaction and subsequent oxidation of the anomeric position yielded the target argentilactone.

scholarly journals Bioinspired Oxidative Cyclization of the Geissoschizine Skeleton for the Enantioselective Total Synthesis of Mavacuran Alkaloids

2019 ◽  
Author(s):  
Maxime Jarret ◽  
Victor Turpin ◽  
Aurélien Tap ◽  
Jean-Francois Gallard ◽  
Cyrille Kouklovsky ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Oxidative Coupling ◽  
Indole Alkaloids ◽  
Oxidative Cyclization ◽  
Total Syntheses ◽  
Enantioselective Total Synthesis ◽  
Biosynthetic Precursor ◽  
Monoterpene Indole Alkaloids ◽  
Coupling Approach

We report the enantioselective total syntheses of mavacurans alkaloids, (+)-taberdivarine H, (+)-16-hydoxymethyl-pleiocarpamine, (+)-16-epi-pleiocarpamine, and their postulated biosynthetic precursor 16-formyl-pleiocarpamine. This family of monoterpene indole alkaloids is a target of choice since some of its members are subunits of intricate bisindole alkaloids such as bipleiophylline. Inspired by the biosynthetic hypothesis, we explored an oxidative coupling approach from the geissoschizine framework to form the N1-C16 bond. Quaternization of the aliphatic nitrogen was key to achieve the oxidative coupling induced by KHMDS/I<sub>2 </sub>since<sub> </sub>it hides the nucleophilicity of the aliphatic nitrogen and locks the required cis conformation.

[1H,15N] N.M.R. Kinetic Studies of Reactions of cis- and trans-[PtCl2(15NH3)(c-C6H1115NH2)] with Guanosine 5'-Monophosphate

1999 ◽  
Vol 52 (3) ◽  
pp. 173 ◽  
Author(s):  
Sarah J. Barton ◽  
Kevin J. Barnham ◽  
Abraha Habtemariam ◽  
Urban Frey ◽  
Rodney E. Sue ◽  
...  
Keyword(s):  
Trans Isomer ◽  
Active Metabolite ◽  
Kinetic Studies ◽  
Trans Influence ◽  
Trans Complex ◽  
Kinetics Of Reaction ◽  
Cis And Trans ◽  
Kinetics Of ◽  
Cis Isomer ◽  
Amine Ligand

cis-[PtCl2(15NH3)(c-C6H11NH2)] is an active metabolite of the oral platinum(IV) anticancer drug cis,trans,cis-[PtCl2(CH3CO2)2(NH2)(c-C6H11NH2)]. Since it is likely that guanine bases on DNA are targets for this drug, we have analysed the kinetics of reaction of this platinum(II) metabolite with guanosine 5′-monophosphate (5′-GMP) at 310 K, pH 7, using [1H, 15N] n.m.r. methods. Reactions of the trans isomer are reported for comparison. The reactions proceed via aquated intermediates, and, for the cis isomer, the rates of aquation and substitution of H2O by 5′-GMP are 2-5 times faster trans to the amine ligand (c-C6H11NH2) compared to trans to NH3 for both the first and second steps. For the trans complex, the first aquation step is c. 3 times faster than for the cis complex, as expected from the higher trans influence of Cl¯, whereas the rate of the second aquation step (trans to N7 of 5′-GMP) is comparable to that trans to NH3. These findings have implications for the courses of reactions with DNA.

Sceptrin as a Potential Biosynthetic Precursor to Complex Pyrrole—Imidazole Alkaloids: The Total Synthesis of Ageliferin.

ChemInform ◽  
2004 ◽  
Vol 35 (36) ◽  
Author(s):  
Phil S. Baran ◽  
Daniel P. O'Malley ◽  
Alexandros L. Zografos
Keyword(s):  
Total Synthesis ◽  
Biosynthetic Precursor

Stereoselective total synthesis of (±)-isocostic and (±)-3-oxoisocostic acids

1982 ◽  
Vol 35 (2) ◽  
pp. 451 ◽  
Author(s):  
R Cruz ◽  
RM Martinez
Keyword(s):  
Total Synthesis ◽  
Trans Isomer ◽  
Michael Addition ◽  
Potassium Salt

Stereoselective total synthesis of the title compounds, two new sesquiterpenes isolated from a Mexican plant, are described. The key step in the synthesis is based on classical santon in syntheses by the stereoselective Michael addition of the potassium salt of ethyl α-cyanoacetate to the dienone(4), to give the cis adduct (5), in an 8 : 2 ratio with the trans isomer. Further appropriate transformation of this cis adduct (5) leads to formation of either isocostic acid (1) or 3-oxoisocostic acid (2).

Sign in / Sign up

Export Citation Format

Share Document