35926-04-6Relevant articles and documents
Enantioselective iridium-catalyzed allylic alkylation of racemic branched alkyl-substituted allylic acetates with malonates
Zhang, Tian-Yuan,Deng, Yi,Wei, Kun,Yang, Yu-Rong
supporting information, p. 1086 - 1089 (2021/02/06)
The regio- and enantioselective allylic substitution of branched alkyl-substituted allylic acetates employing malonates has been achieved through a process that calls for Krische's πallyliridium C,O-benzoate catalyst. The protocol reported herein can be applied to a diverse set of branched alkyl substrates that are generally not well tolerated in the other two types of Ir-catalyzed allylation.
Ascaroside Signaling in the Bacterivorous Nematode Caenorhabditis remanei Encodes the Growth Phase of Its Bacterial Food Source
Dolke, Franziska,Dong, Chuanfu,Bandi, Siva,Paetz, Christian,Glauser, Gaétan,Von Reu?, Stephan H.
supporting information, p. 5832 - 5837 (2019/08/26)
A novel class of species-specific modular ascarosides that integrate additional fatty acid building blocks was characterized in the nematode Caenorhabditis remanei using a combination of HPLC-ESI-(-)-MS/MS precursor ion scanning, microreactions, HR-MS/MS, MSn, and NMR techniques. The structure of the dominating component carrying a cyclopropyl fatty acid moiety was established by total synthesis. Biogenesis of this female-produced male attractant depends on cyclopropyl fatty acid synthase (cfa), which is expressed in bacteria upon entering their stationary phase.
A Re2O7catalyzed cycloetherification of monoallylic diols
Wan, Xiaolong,Hu, Jiadong,Xu, Dongyang,Shang, Yang,Zhen, Yanxia,Hu, Chenchen,Xiao, Fan,He, Yu-Peng,Lai, Yisheng,Xie, Weiqing
supporting information, p. 1090 - 1093 (2017/03/02)
A Re2O7catalyzed cycloetherification of monoallylic diols is described. The reaction features short reaction time, mild reaction conditions and exclusive E selectivity. A wide range of monoallylic alcohols with alkyl or aryl substituents on olefin smoothly undergo ring closure to deliver corresponding oxa-heterocycles. The reaction is also operationally simple and not sensitive to air and moisture.
Regioselective Asymmetric Allylic Alkylation Reaction of α -Cyanoacetates Catalyzed by a Heterobimetallic Platina-/Palladacycle
Weiss, Marcel,Holz, Julia,Peters, Ren
, p. 210 - 227 (2016/01/20)
Allylic substitution reactions provide a valuable tool for the functionalization of CH acidic pronucleophiles. Often, control over the stereocenter generated at the nucleophilic reactant is still a challenge. The majority of studies that address this issue employ metal complexes with a low metal oxidation state (e.g. Pd0) to form allyl complexes through oxidative addition. In this article we describe the use of heterobimetallic PtII/PdII complexes, which probably activate the olefinic substrates through an SN2′ pathway. The reaction of α-cyanoacetates delivers linear allylation products with exclusive regioselectivity and high E/Z-selectivity for the new C=C double bond. Although the enantioselectivities attained are moderate, they are significantly higher than with related mono-PdII or -PtII catalysts or the corresponding bis-PdII complex, which indicates cooperation of the different metals. Control experiments suggest simultaneous activation of both reaction partners.
Ni- and pd-catalyzed synthesis of substituted and functionalized allylic boronates
Zhang, Ping,Roundtree, Ian A.,Morken, James P.
supporting information; scheme or table, p. 1416 - 1419 (2012/06/01)
Two highly efficient and convenient methods for the synthesis of functionalized and substituted allylic boronates are described. In one procedure, readily available allylic acetates are converted to allylic boronates catalyzed by Ni/PCy3 or Ni/PPh3 complexes with high levels of stereoselectivity and in good yields. Alternatively, the borylation can be accomplished with commercially available Pd catalysts [e.g., Pd 2(dba)3, PdCl2, Pd/C], starting with easily accessed allylic halides.
Palladacyclic imidazoline-naphthalene complexes: Synthesis and catalytic performance in Pd(II)-catalyzed enantioselective reactions of allylic trichloroacetimidates
Cannon, Jeffrey S.,Frederich, James H.,Overman, Larry E.
supporting information; body text, p. 1939 - 1951 (2012/04/23)
A new family of air- and moisture-stable enantiopure C,N-palladacycles (PIN-acac complexes) were prepared in good overall yield in three steps from 2-iodo-1-naphthoic acid and enantiopure β-amino alcohols. Three of these PIN complexes were characterized by single-crystal X-ray analysis. As anticipated, the naphthalene and imidazoline rings of PIN-acac complexes 18a and 18b were canted significantly from planarity and projected the imidazoline substituents R1 and R2 on opposite faces of the palladium square plane. Fifteen PIN complexes were evaluated as catalysts for the rearrangement of prochiral (E)-allylic trichloroacetimidate 19 (eq 2) and the SN2′ allylic substitution of acetic acid with prochiral (Z)-allylic trichloroacetimidate 23. Although these complexes were kinetically poor catalysts for the Overman rearrangement, they were good catalysts for the allylic substitution reaction, providing branched allylic esters in high yield. However, enantioselectivities were low to moderate and significantly less than that realized with palladacyclic complexes of the COP family. Computational studies support an anti-acetoxypalladation/syn-deoxypalladation mechanism analogous to that observed with COP catalysts. The computational study further suggests that optimizing steric influence in the vicinity of the carbon ligand of a chiral C,N-palladacycle, rather than near the nitrogen heterocycle, is the direction to pursue in future development of improved enantioselective catalysts of this motif.
Catalytic asymmetric synthesis of chiral allylic esters
Cannon, Jeffrey S.,Kirsch, Stefan F.,Overman, Larry E.
supporting information; experimental part, p. 15185 - 15191 (2010/12/25)
A broadly useful catalytic enantioselective synthesis of branched allylic esters from prochiral (Z)-2-alkene-1-ols has been developed. The starting allylic alcohol is converted to its trichloroacetimidate intermediate by reaction with trichloroacetonitrile, either in situ or in a separate step, and this intermediate undergoes clean enantioselective SN2′ substitution with a variety of carboxylic acids in the presence of the palladium(II) catalyst (Rp,S)-di-μ-acetatobis[(η5- 2-(2′-(4′-methylethyl)oxazolinyl)cyclopentadienyl-1-C,3′-N) (η4-tetraphenylcyclobutadiene)cobalt]dipalladium, (R p,S)-[COP-OAc]2, or its enantiomer. The scope and limitations of this useful catalytic asymmetric allylic esterification are defined.
A novel one-pot conversion of allyl alcohols into primary allyl halides mediated by acetyl halide
Kishali, Nurhan,Polat, M. Fatih,Altundas, Ramazan,Kara, Yunus
, p. 67 - 72 (2008/09/17)
A new and simple method for the synthesis of the primary allyl chlorides and bromides 9-16 from the secondary or tertiary allyl alcohols 3-8 and acyl halide was developed (Scheme 2, Table 1). Non-commercially available secondary and tertiary allyl alcohols were synthesized from the related ketones and aldehydes via the addition of vinylmagnesium chloride. Mechanistic studies indicate that the alcohols were first acetylated by the acetyl halide and then protonated prior to substitution by the halide, Cl- or Br -, via an 5N2′ reaction, to yield the primary halides (Scheme 5).
The Reaction between Acyl Halides and Alcohols: Alkyl Halide vs. Ester Formation
Strazzolini, Paolo,Giumanini, Angelo G.,Verardo, Giancarlo
, p. 217 - 254 (2007/10/02)
In the reaction between an acyl halide and an alcohol the thermodynamically favoured products are the free carboxylic acid and the alkyl halide.The initial reaction is, generally, the formation of an ester and HHal.When the alcohol is very prone to yield an alkyl cation upon protonation by HHal, formed H2O exhibited a superior reactivity and competed successfully with the alcohol for the acyl halide making, therefore, ester formation practically confined to a triggering role.But, in those cases where the cation is less easily formed, ester formation was favoured and, consequently, became the necessary elementary step towards alkyl halide formation.Tis final product, on the other hand, might be extremely slow to form in an SN2 reaction between the protonated ester function and the halide ion.In these instances, therefore, as well as in the cases when a basic solvent competes for the proton of HHal, the ester is the final product.A notable exception of the situation above outlined, is given by α-hydroxy-α-phenylbenzeneacetic acid (2y), which appears to undergo direct chlorine-hydroxyl interchange through a quaternary intermediate (E), in the end collapsing to α-chloro-α-phenyl-benzeneacetic acid (4y).Different systems were compared using CH2Cl2 as a solvent under strictly similar conditions.Some 28 different substrates were tested for reaction with AcCl (1a), whereas the action of eight acyl halides (a) against (RS)-α-methylbenzenemethanol (2n) and α-phenylbenzenemethanol (2p), as well as the effect of five different solvents on the reaction between two alcohols (2p and 2-methyl-2-propanol, 2c) with 1a, were observed.
COORDINATION AND CATALYTIC REACTIONS OF UNSATURATED COMPOUNDS. VIII. HETEROGENEOUS CATALYTIC ACETOXYLATION OF 1-HEXENE AND CYCLOHEXENE
Devekki, A. V.,Yakushkin, M. I.,Egor'kov, A. N.,Belyaeva, N. V.,Mozzhukhina, T. N.,et al.
, p. 1680 - 1684 (2007/10/02)
During the acetoxylation of 1-hexene and cyclohexene in acetic acid in the presence of atmospheric oxygen and intermetallic compounds based on palladium and rhodium the ester groups are introduced into the substrate molecule.In the case of 1-hexene, the monoacetates of 1,2-hexanediol and 3-acetoxy-1-hexene are formed preferentially.The reactivity of the cyclic alkene is more clearly defined than that of the acyclic analog, and the catalyzate contains the cis- and trans-diacetoxy derivatives, 3-acetoxycyclohexene, and the products from ring concentration.The difference in the catalytic activity of the palladium and rhodium intermetallic compounds shows up mainly in the actoxylation of 1-hexene.The ring concentration products are evidently formed in the stages involving the transformation of the actoxonium ion.
