Refernces
10.1016/S0957-4166(01)00486-4
The research aimed to investigate the relationship between the chirality of allylic alcohols and their anti-rice blast fungus activity. The study was motivated by the discovery of various oxygenated unsaturated fatty acids in rice plants, which play a crucial role in defending against rice blast fungus. Specifically, the allylic alcohols 16-hydroxy-γ-linolenic acid 1, 9-hydroxylinoleic acid 2, and 13-hydroxylinoleic acid 3 were of interest, as they accumulate in infected rice plants. The researchers synthesized both enantiomers of these allylic alcohols starting from the original fatty acids 4 and 5 and assessed their anti-fungal activities. The conclusion drawn from the study was that there was no noticeable correlation between the activity and chirality of the allylic alcohols. Chemicals used in the process included γ-linolenic and linoleic acids, hydroperoxy fatty acids, allylic alcohols, and epoxy fatty acids, among others. The synthesis involved various reagents and solvents such as n-BuLi, Pr2NH, CH2N2, (PhCO)2O/Et3N, and HPLC for purification and separation, as well as lipase PS, vinyl acetate, and thiacrown ether for the resolution of enantiomers.
10.1016/S0960-894X(98)00338-2
The research focuses on the synthesis and pharmacological evaluation of all stereoisomers of 2-(2-carboxy-3,3-difluorocyclopropyl)glycines (F2CCGs) using (R)-2,3-O-isopropylideneglyceraldehyde as a chiral precursor. The study investigates the effect of introducing fluorine atoms onto the cyclopropane ring of conformationally restricted analogs of L-glutamate (CCGs) on their receptor subtype specificities. Key chemicals involved in the synthesis include difluorocarbene, allylic alcohol derivatives, and various reagents for functional group transformations such as TBDMS-Cl, imidazole, PhCOOH, DEAD, Ph3P, (PhO)2P(O)N3, Boc2O, NaHCO3, RuCl3, NaIO4, CH2N2, Ti(OBn)4, and HCl. The pharmacological evaluation reveals that L-F2CCG-I, corresponding to an extended form of L-glutamate, is a potent agonist for metabotropic glutamate receptors (mGluRs), showing enhanced activity compared to L-CCG-I. Other isomers exhibit various activities related to NMDA receptors and mGluRs, highlighting the impact of fluorine substitution on receptor activation and providing valuable insights for the study of glutamate receptors.
10.1021/ja9719182
The research introduces a novel and efficient method for synthesizing allylic alcohols with tri- and tetrasubstituted alkenes. The purpose of this study is to address the challenge of creating these complex molecules in a single operation while maintaining stereochemical integrity. The researchers developed a nickel-catalyzed cyclization/alkylation protocol using ynals and organozincs to produce cyclic allylic alcohols and a three-component coupling involving alkynes, aldehydes, and organozincs to produce acyclic allylic alcohols. Key chemicals include ynals, organozincs generated from organolithiums or organomagnesiums and anhydrous zinc chloride, and nickel catalysts such as Ni(COD)2. The method allows for the stereoselective introduction of both E and Z isomers of the alkenes from a common intermediate, with complete control over alkene stereochemistry. The study concludes that this method is general, efficient, and experimentally simple, conducted at 0 °C with readily accessible reagents. The procedures are highly chemoselective, regioselective, and stereoselective, yielding allylic alcohols with high purity. The researchers suggest that oxametallacycles are likely intermediates in the transformations and that both reductive and alkylative cyclization products are derived from a common intermediate. Further refinements, including catalytic asymmetric variants and mechanistic studies, are currently under investigation.
10.1016/S0040-4039(00)84713-9
The study investigates the synthesis and antibacterial activity of various derivatives of penicillin. The researchers aimed to create 6a-carboxy and 6a-carbamoyl penicillins, which are structural analogues of previously studied 6a-(hydroxymethyl) and 6a-formyl penicillins known for their stability to β-lactamases and antibacterial activity. Key chemicals involved include 6a-(hydroxymethyl)penicillanate and 6a-formyl penicillin, which served as starting materials. The researchers used reagents such as t-butyl alcohol, chromium trioxide, pyridine, acetic anhydride, and allyl alcohol to oxidize and esterify these compounds, ultimately synthesizing various penicillin carboxylates. They also attempted to prepare a 6a-carbamoyl penicillin using mixed anhydride formation and ammonia. Despite successful synthesis of several derivatives, including the allyl ester and pivaloyloxymethyl ester, the final penicillin products exhibited poor antibacterial activity.
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