4541-69-9Relevant articles and documents
Regio- And Stereoselective (S N2) N -, O -, C - And S -Alkylation Using Trialkyl Phosphates
Banerjee, Amit,Hattori, Tomohiro,Yamamoto, Hisashi
, (2021/06/16)
Bimolecular nucleophilic substitution (S N 2) is one of the most well-known fundamental reactions in organic chemistry to generate new molecules from two molecules. In principle, a nucleophile attacks from the back side of an alkylating agent having a suitable leaving group, most commonly a halide. However, alkyl halides are expensive, very harmful, toxic and not so stable, which makes them problematic for laboratory use. In contrast, trialkyl phosphates are inexpensive, readily accessible and stable at room temperature, under air, and are easy to handle, but rarely used as alkylating agents in organic synthesis. Here, we describe a mild, straightforward and powerful method for nucleophilic alkylation of various N -, O -, C - and S -nucleophiles using readily available trialkyl phosphates. The reaction proceeds smoothly in excellent yield, and quantitative yield in many cases, and covers a wide range of substrates. Further, the rare stereoselective transfer of secondary alkyl groups has been achieved with inversion of configuration of chiral centers (up to 98% ee).
A step forward in solvent knitting strategies: Ruthenium and gold phosphine complex polymerization results in effective heterogenized catalysts
Valverde-González, Antonio,Marchal, Gwendoline,Maya, Eva M.,Iglesias, Marta
, p. 4552 - 4560 (2019/09/09)
Porous polymers based on ruthenium and gold triphenylphosphine complexes (KPhos(Ru), KPhos(Ru)Bi, KPhos(AuCl) and KPhos(AuNTf2)) were prepared via a cost-effective solvent knitting method with [RuHClCO(PPh3)3] or AuXPPh3 (X = Cl, NTf2) as single monomers or combined with biphenyl, which represents a further approach to obtain heterogenized catalysts. The resulting materials mainly preserve the metal coordination environment of their parent complexes, are stable up to 350 °C and have reasonable surface areas (250-300 m2 g-1 for KPhos(Ru)-polymers). KPhos(Ru)s selectively catalyze the imination of alcohols in the presence of base and the results for KPhos(Au)s show they are effective for the intermolecular hydration and hydroamination of alkynes. These materials can be reused several times without significant loss of activity. This novel and simple method affords heterogenized catalysts that combine the reactivity and selectivity of their homogeneous counterparts with the stability and reusability of a heterogeneous framework.
Reaction Intermediates Kinetics in Solution Investigated by Electrospray Ionization Mass Spectrometry: Diaurated Complexes
Ja?íková, Lucie,Anania, Mariarosa,Hybelbauerová, Simona,Roithová, Jana
supporting information, p. 13647 - 13657 (2015/11/10)
A new method to investigate the reaction kinetics of intermediates in solution by electrospray ionization mass spectrometry is presented. The method, referred to as delayed reactant labeling, allows investigation of a reaction mixture containing isotopically labeled and unlabeled reactants with different reaction times. It is shown that we can extract rate constants for the degradation of reaction intermediates and investigate the effects of various reaction conditions on their half-life. This method directly addresses the problem of the relevance of detected gaseous ions toward the investigated reaction solution. It is demonstrated for geminally diaurated intermediates formed in the gold mediated addition of methanol to alkynes. Delayed reactant labeling allows us to directly link the kinetics of the diaurated intermediates with the overall reaction kinetics determined by NMR spectroscopy. It is shown that the kinetics of protodeauration of these intermediates mirrors the kinetics of the addition of methanol demonstrating they are directly involved in the catalytic cycle. Formation as well as decomposition of diaurated intermediates can be drastically slowed down by employing bulky ancillary ligands at the gold catalyst; the catalytic cycle then proceeds via monoaurated intermediates. The reaction is investigated for 1-phenylpropyne (Ph-CC-CH3) using [AuCl(PPh3)]/AgSbF6 and [AuCl(IPr)]/AgSbF6 as model catalysts. Delayed reactant labeling is achieved by using a combination of CH3OH and CD3OH or Ph-CC-CH3 and Ph-CC-CD3.
