5398-04-9Relevant academic research and scientific papers
Harnessing the Power of the Asymmetric Grignard Synthesis of Tertiary Alcohols: Ligand Development and Improved Scope Exemplified by One-Step Gossonorol Synthesis
Gilheany, Declan G.,Kavanagh, Saranna E.
supporting information, p. 8198 - 8203 (2020/11/18)
A series of N-substituted cyclohexyldiaminophenolic ligands for the asymmetric Grignard synthesis of tertiary alcohols is reported. The 2,5-dimethylpyrrole-decorated ligand led to improved enantioselectivities and broadened the scope of the methodology. As an exemplar, we report an unprecedented highly selective one-step synthesis of gossonorol in 93% ee, also constituting the shortest formal syntheses of natural products boivinianin B and yingzhaosu C.
Structural effects on the β-scission reaction of alkoxyl radicals. Direct measurement of the absolute rate constants for ring opening of benzocycloalken-1-oxyl radicals
Bietti, Massimo,Lanzalunga, Osvaldo,Salamone, Michela
, p. 1417 - 1422 (2007/10/03)
(Chemical Equation Presented) The absolute rate constants for β-scission of a series of benzocycloalken-1-oxyl radicals and of the 2-(4-methylphenyl)-2-butoxyl radical have been measured directly by laser flash photolysis. The benzocycloalken-1-oxyl radicals undergo ring opening with rates which parallel the ring strain of the corresponding cycloalkanes. In the 1-X-indan-1-oxyl radical series, ring opening is observed when X = H, Me, whereas exclusive C-X bond cleavage occurs when X = Et. The factors governing the fragmentation regioselectivity are discussed.
Vilsmeier-Haack reaction of tertiary alcohols: Formation of functionalised pyridines and naphthyridines
Thomas,Asokan
, p. 2583 - 2587 (2007/10/03)
Vilsmeier-Haack reaction of 2-arylpropan-2-ols proceeds with multiple iminoalkylations leading to the formation of conjugated iminium salts which on ammonium acetate-induced cyclisation afford 4-arylnicotinaldehydes in good yields. Tertiary alcohols derived from aliphatic or alicyclic ketones by the addition of methyl Grignard are converted into substituted pyridines and naphthyridines by the action of Vilsmeier's reagent in N,N-dimethylformamide followed by nucleophile-assisted cyclisation in the presence of ammonium acetate.
The Importance of Resonance Stabilization in the Benzylic Solvolysis. Substituent Effects on the Solvolysis of α,α-Diisopropylbenzyl Chlorides
Fujio, Mizue,Nakata, Kazuhide,Kuwamura, Takashi,Nakamura, Hirotaka,Saeki, Yoshihiro,et al.
, p. 8309 - 8312 (2007/10/02)
The substituent effect on the solvolysis of α,α-diisopropylbenzyl chlorides can be described in terms of ?+ value.No significant steric loss of resonance was observed by introducing two bulky isopropyl groups into benzylic reaction center.
Studies on the Regioselectivities in the Oxidation of Simple Alkyl Aromatic Hydrocarbons by Molecular Oxygen
Pritzkow, Wilhelm,Thomas, Gerda,Willecke, Lothar
, p. 847 - 851 (2007/10/02)
The products of the autoxidation of various simple alkyl aromatic hydrocarbons were reduced by LiAlH4, and the alcohols formed were determined by gas chromatography.In the cases of 2-phenylbutane, 3-phenylpentane, and 2-p-tolylbutane a considerable fragmentation of the intermediate tertiary alkoxy radicals was proved.On the basis of the analytical results relative reaction rates of the various C-H bonds in the hydrocarbons studied were calculated.It is shown that the attack at C-H bonds which are not activated by the aromatic nucleus cannot be neglected and may be of great importance for the kinetics of the oxidation of alkyl aromatic hydrocarbons.
Determination of Relative Autoxidation Rates of Simple Alkylaromatic Hydrocarbons by Competitive Reactions
Pritzkow, Wilhelm,Thomas, Gerda,Willecke, Lothar
, p. 945 - 952 (2007/10/02)
Relative rates of oxidative attack at the C-H bonds in α-position to the aromatic nucleus were determined for 10 simple alkylaromatic hydrocarbons.The results obtained by competitive oxidations of binary mixtures were shown to be consistent.From these results and the regioselectivity data already published, relative reactivities referring to the tertiary C-H bond of cumene were calculated for all C-H bonds of the hydrocarbons studied.As expected, p-alkyl groups increase the reactivity of C-H bonds in α-position to the aromatic nucleus.On the other hand, large alky l groups, bound to the α-C atoms, decrease the reactivity of the α-C-H bonds.
