138741-39-6Relevant academic research and scientific papers
Insecticidal 1,3-Oxathianes and Their Oxides
Palmer, Christopher J.,Casida, John E.
, p. 498 - 502 (1995)
1,3-Oxathianes with suitable 2- and 5-substituents are highly potent insecticides.In some cases 1,3-oxathiane 3-oxides and 1,3-oxathiane 3,3-dioxides derived by m-chloroperoxybenzoic acid oxidation of the 1,3-oxathianes are even more effective.Housefly LD50s for trans-5(e)-tert-butyl-2(e)-(4-ethynylphenyl)-1,3-oxathiane 3,3-dioxide are 0.3 and 0.03 μg/g alone and with piperonyl butoxide, respectively.It is the most insecticidal analogue in the oxathiane series and approaches the potency of (1R)-cis-permethrin.Keywords: Oxathianes; dioxanes; dithianes; trioxabicyclooctanes; insecticide
Enantioselective Desymmetrization of 2-Aryl-1,3-propanediols by Direct O-Alkylation with a Rationally Designed Chiral Hemiboronic Acid Catalyst That Mitigates Substrate Conformational Poisoning
Estrada, Carl D.,Ang, Hwee Ting,Vetter, Kim-Marie,Ponich, Ashley A.,Hall, Dennis G.
supporting information, (2021/04/07)
Enantioselective desymmetrization by direct monofunctionalization of prochiral diols is a powerful strategy to prepare valuable synthetic intermediates in high optical purity. Boron acids can activate diols toward nucleophilic additions; however, the design of stable chiral catalysts remains a challenge and highlights the need to identify new chemotypes for this purpose. Herein, the discovery and optimization of a bench-stable chiral 9-hydroxy-9,10-boroxarophenanthrene catalyst is described and applied in the highly enantioselective desymmetrization of 2-aryl-1,3-diols using benzylic electrophiles under operationally simple, ambient conditions. Nucleophilic activation and discrimination of the enantiotopic hydroxy groups on the diol substrate occurs via a defined chairlike six-membered anionic complex with the hemiboronic heterocycle. The optimal binaphthyl-based catalyst 1g features a large aryloxytrityl group to effectively shield one of the two prochiral hydroxy groups on the diol complex, whereas a strategically placed "methyl blocker"on the boroxarophenanthrene unit mitigates the deleterious effect of a competing conformation of the complexed diol that compromised the overall efficiency of the desymmetrization process. This methodology affords monoalkylated products in enantiomeric ratios equal or over 95:5 for a wide range of 1,3-propanediols with various 2-aryl/heteroaryl groups.
Conformationally constrained 2-methylidene 1,3-oxathiane S-oxides: Synthesis and nucleophilic additions
Weingand, Daniel,Kiefer, Claude,Podlech, Joachim
, p. 1261 - 1268 (2015/03/05)
The properties of vinyl sulfoxides are significantly influenced by stereoelectronic effects, where the relative orientation of sulfoxide group and alkene moiety is responsible for reactivity and selectivity, e.g., in the addition of nucleophiles. Conformationally constrained derivatives of 2-methylidene 1,3-oxathiane S-oxides allow the quantification of stereoelectronic effects. Suitable substrates were prepared by oxidation of 2-hydroxymethyl-1,3-oxathianes and pyrolysis of the respective xanthogenates. Nucleophilic additions of ethyl thiolate, piperidine, and dimethyl malonate anion are over 100 times faster to axial sulfoxides than to the respective equatorial substrates. The oxathiane derivatives turned out to be about 1000 times less reactive than the respective 1,3-dithianes.
Mechanism of esterification of 1,3-dimethylamino alcohols by N-acetylimidazole in acetonitrile and the influence of alkyl and geminal dialkyl substitution upon the rate
Madder, Annemieke,Sebastian, Sonny,Van Haver, Dirk,De Clercq, Pierre J.,Maskill, Howard
, p. 2787 - 2793 (2007/10/03)
3-(Dimethylamino)propan-1-ol and seven derivatives with alkyl substituents at the 2-position have been prepared by conventional methods, and second-order rate constants for their esterification by N-acetylimidazole in acetonitrile have been measured under pseudo-first-order conditions both by 1H NMR spectroscopy at a single temperature (23°C) and by a UV spectroscopic method over the temperature range 25-65°C. Evidence is presented that the intermolecular esterifications proceed via an initial rate-determining intramolecular general base catalysed formation of a cyclic tetrahedral intermediate. Effective molarities compared with the third-order reactions of simpler alcohols with acetylimidazole catalysed by triethylamine are estimated to be 13-14 mol dm-3, but alkyl substitution at the 2-position of the amino alcohol has only a modest effect upon reaction rates. All reactions have substantial negative entropies of activation and only modest enthalpies of activation as expected for concerted bimolecular reactions with highly ordered transition structures. Three structurally related carbocyclic amino alcohols constitute a short isokinetic series with the isokinetic temperature very close to the experimental range. Along this series, decreasing enthalpies of activation are almost exactly balanced in their contributions to the overall free energy of activation near room temperature by increasingly negative entropies of activation.
Anchoring substitution in acyclic 1,3-amino alcohols. Asymmetric reductions with chiral modifications of lithium aluminum hydride and borane
Steels,De Clercq,Declercq
, p. 599 - 602 (2007/10/02)
Chiral modifications of LAH and amino alcohols 1b and 2 give erratic results in the asymmetric reduction of acetophenone. In the presence of chiral tetrahydro-1,3,2-oxazaborines, derived from 1a, however, the borane reduction of acetophenone consistently
Alkynylphenyl-substituted 1,3-oxathione compounds with pesticidal activity
-
, (2008/06/13)
Pesticidally-active alkynylphenyl-substituted 1,3-oxathianes and related substituted compounds of the formula: STR1 and their use in controlling pests such as arthropods and helminths are described.
