138432-95-8Relevant academic research and scientific papers
Fe-Catalyzed Anaerobic Mukaiyama-Type Hydration of Alkenes using Nitroarenes
Bhunia, Anup,Bergander, Klaus,Daniliuc, Constantin Gabriel,Studer, Armido
supporting information, p. 8313 - 8320 (2021/03/08)
Hydration of alkenes using first row transition metals (Fe, Co, Mn) under oxygen atmosphere (Mukaiyama-type hydration) is highly practical for alkene functionalization in complex synthesis. Different hydration protocols have been developed, however, control of the stereoselectivity remains a challenge. Herein, highly diastereoselective Fe-catalyzed anaerobic Markovnikov-selective hydration of alkenes using nitroarenes as oxygenation reagents is reported. The nitro moiety is not well explored in radical chemistry and nitroarenes are known to suppress free radical processes. Our findings show the potential of cheap nitroarenes as oxygen donors in radical transformations. Secondary and tertiary alcohols were prepared with excellent Markovnikov-selectivity. The method features large functional group tolerance and is also applicable for late-stage chemical functionalization. The anaerobic protocol outperforms existing hydration methodology in terms of reaction efficiency and selectivity.
An Iron(III) Catalyst with Unusually Broad Substrate Scope in Regioselective Alkylation of Diols and Polyols
Ren, Bo,Ramstr?m, Olof,Zhang, Qiang,Ge, Jiantao,Dong, Hai
, p. 2481 - 2486 (2016/02/12)
In this study, [Fe(dibm)3] (dibm=diisobutyrylmethane) is shown to have unusually broad scope as a catalyst for the selective monoalkylation of a diverse set of 1,2- and 1,3-diol-containing structures. The mechanism is proposed to proceed via a cyclic dioxolane-type intermediate, formed between the iron(III) species and two adjacent hydroxyl groups. This approach represents the first transition-metal catalysts that are able to replace stoichiometric amounts of organotin reagents in regioselective alkylation. The reactions generally lead to very high regioselectivities and high yields, on par with, or better than, previous methods used for regioselective alkylation.
Stereoselective Synthesis of Z-α,β-Unsaturated Sulfones Using Peterson Reagents
Ando, Kaori,Wada, Tomohiro,Okumura, Miho,Sumida, Hiroshi
supporting information, p. 6026 - 6029 (2016/01/09)
New Peterson reagents were prepared by introducing alkyloxy groups on the silicon atom in order to fix the conformation of the sulfone anion. The reagents 1d and 1e reacted with a variety of aldehydes after the treatment with Li-base to give Z-α,β-unsaturated sulfones with up to >99:1 selectivity in good to excellent yields. For the reaction with aliphatic aldehydes, CPME (cyclopentyl methyl ether) is the choice of solvent, while DME (1,2-dimethoxyethane) gave higher selectivity for the reaction with aromatic aldehydes.
Cyclic Ether Synthesis via Palladium-Catalyzed Directed Dehydrogenative Annulation at Unactivated Terminal Positions
Thompson, Samuel J.,Thach, Danny Q.,Dong, Guangbin
supporting information, p. 11586 - 11589 (2015/09/28)
Here, a palladium-catalyzed functionalization of unactivated sp3 C-H bonds with internal alcohol nucleophiles is described. Directed by an oxime-masked alcohol, annulation chemoselectively occurs at the β position, leading to a range of aliphatic cyclic ethers with four- to seven-membered rings. Tethered primary, secondary, and tertiary free hydroxyl groups can all react to give the corresponding cyclized products. In addition, benzyl and silyl protected alcohols can also be directly coupled. An sp3 C-H activation/intramolecular SN2 pathway was proposed.
Novel silyl linkers for solid-phase synthesis
Meloni, Marco M.,Brown,White, Peter D.,Armour, Duncan
, p. 6023 - 6026 (2007/10/03)
The syntheses of two silyl chloride resins, 2 and 10 are described starting from Merrifield resin, 3-methyl-1,3-butanediol and diphenyldichlorosilane or dimethyldichlorosilane, respectively. The silyl chloride resin 2 was used for the attachment of 1° alcohols, 2° alcohols and phenols to the solid phase. A preliminary study of the stability of the diphenylsiloxane linker towards certain reaction conditions was also carried out. A more reactive silyl chloride resin 10 was found to be suitable for the attachment of 3° alcohols to the solid phase.
An Enantioselective Route to (-)-Δ9(12)-Capnellene Employing Silyl Group Directed Stereo Control
Asaoka, Morio,Obuchi, Kazuyuki,Takei, Hisashi
, p. 655 - 660 (2007/10/02)
A formal synthesis of a marine natural product (-)-Δ9(12)-capnellene has been achieved by employing silyl group directed stereo control, starting from (-)-2-methyl-4-trimethylsilyl-2-cyclopenten-1-one.
Chelates as intermediates in nucleophilic additions to alkoxy ketones according to Cram's rule (cyclic model)
Chen, Xiangning,Hortelano, Edwin R.,Eliel, Ernest L.,Frye, Stephen V.
, p. 1778 - 1784 (2007/10/02)
Chelates have been considered intermediates in the often highly stereoselective reactions of α-alkoxy and similarly substituted ketones for over 30 years,10 but without mechanistic evidence. It is now shown, by stop-flow ("rapid injection") NMR kinetics,15 that the specific rates of reaction of ketones C6H5COCH(OR)CH3 with Me2Mg, where R = (i-Pr)3 ("TIPS"), t-BuPh2Si, t-BuMe2Si, Et3Si, Me3Si, and Me, parallel the diastereoselectivity of the reaction; i.e., the fastest reacting compound (R = Me) is the one which gives the highest proportion of the product predicted by Cram's chelate rule. The major product of the slowest reacting compound (R = TIPS) is not in accord with Cram's chelate rule, and this compound reacts at the same specific rate as the parent, C6H5COCH2CH3. This is in accord with earlier work indicating that TIPSO does not chelate. Compounds intermediate in the series react at intermediate rates and give the two diastereomeric products in proportions which can be calculated by assuming two competing reactions (cf. Figure 2): one proceeding via the chelated transition states giving the product predicted by the chelate rule and one not involving chelation which gives the same product composition as the R = TIPS compound. Direct steric effects on carbonyl reactivity due to the remote bulky silyloxy substituents have been excluded by the study of carbon analogues bearing similar bulky groups. Thus, the kinetic effect in the above series appears to be due to steric hindrance to chelation; hence, the parallel of specific rate and stereoselectivity demonstrates that high stereoselectivity is associated with strong chelation, as postulated by Cram and Kopecky in 1959.10.
