2886-59-1Relevant academic research and scientific papers
Reduction method of electronic salt reaction liquid and unsaturated aromatic hydrocarbon compound
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Paragraph 0080-0083, (2021/11/10)
To the reduction method, tetrahydrofuran is used as a solvent and an electron trapping agent, metal lithium is used as a reducing agent, tertiary butanol is used as a reducing agent, and the unsaturated aromatic hydrocarbon compound is reduced under -10 - 0 °C conditions. The raw material tetrahydrofuran is used in the invention. Metal lithium and tert-butyl alcohol are all conventional chemical products, and are simple and easy to obtain. After the reaction is finished, excess lithium and solvent are recovered, and directly used to realize low cost, low pollution and high yield.
Rhodium(I)-Catalyzed Enantioselective C(sp3)—H Functionalization via Carbene-Induced Asymmetric Intermolecular C—H Insertion?
Liu, Bo,Xu, Ming-Hua
supporting information, p. 1911 - 1915 (2021/05/31)
Transition-metal-catalyzed C—H insertion of metal-carbene represents an excellent and powerful approach for C—H functionalization. However, despite remarkable advances in metal-carbene chemistry, transition metal catalysts that are capable of enantioselective intermolecular carbene C—H insertion are mainly constrained to dirhodium(II) and iridium(III)-based complexes. Herein, we disclose a new version of asymmetric carbene C—H insertion reaction with rhodium(I) catalyst. A highly enantioselective rhodium(I) complex-catalyzed C(sp3)—H functionalization of 1,4-cyclohexadienes with α-aryl-α-diazoacetates was successfully developed. By using chiral bicyclo[2.2.2]-octadiene as ligand, rhodium(I)-carbene-induced asymmetric intermolecular C—H insertion proceeds smoothly at room temperature, allowing access to a diverse variety of α-aryl-α-cyclohexadienyl acetates and gem-diaryl-containing acetates in good yields with good to excellent enantioselectivities (up to 99% ee). Furthermore, the synthetic utility of the reaction was highlighted by facile synthesis of a novel cannabinoid CB1 receptor ligand. This method may offer a new opportunity for the development of therapeutically exploitable cannabinoid receptor type ligands in medicinal chemistry.
Comparison of the singlet oxygen ene reactions of cyclic versus acyclic β,γ-unsaturated ketones: An experimental and computational study Dedicated to Professor Waldemar Adam on the occasion of his 75th birthday
Griesbeck, Axel G.,Goldfuss, Bernd,Leven, Matthias,De Kiff, Alan
supporting information, p. 2938 - 2941 (2013/06/27)
The photooxygenation of two β,γ-unsaturated ketones was studied by experimental and computational methods: 5-methyl-hex-4-en-2-one (1) and cyclohex-3-en-1-one (6) as model compounds for acyclic versus cyclic deconjugated enones. The open-chain substrate delivered a 1:1 mixture of regioisomers 2a,b following the established cis-selectivity model whereas the cyclic substrate reacts with 1O2 to give preferentially the conjugated product 7. This effect is in agreement with the mechanistic two-stage no-intermediate model and on a computational level corresponds to a regioselectivity control following the steepest decent pathway from the corresponding transition stages in a valley ridge potential energy surface region.
Temporary thio-derivatization in the synthesis of (+)-4-acetylbromoxone
O'Byrne, Aisling,O'Reilly, Steven,Tighe, Catherine,Evans, Paul,Ciuffini, Laura,Gabriella Santoro
, p. 5936 - 5938 (2013/01/13)
A stereocontrolled synthesis of the marine natural products (+)-bromoxone (1) and (+)-4-acetylbromoxone (2) is reported. The sequence features the enzymatic kinetic resolution of 4-hydroxycyclohexenone (6) via its S-benzyl adduct. Thereafter, a base-mediated elimination-silylation generated an optically active (-)-4S-4-tert-butyldimethylsilyoxycyclohexenone (5), which then underwent diastereoselective epoxidation. Saegusa-Ito oxidation enabled formation of the corresponding α,β-unsaturated ketone 13. Bromination-elimination and subsequent removal of the silicon protecting group afforded (+)-bromoxone (1) which was converted into (+)-(4S,5R,6R)-4-acetoxy-2- bromo-5,6-epoxycyclohex-2-enone (2) [(+)-4-acetylbromoxone]. Using a luciferase gene reporter assay ED50 for NFκB inhibition of 9 μM was determined.
The thio-adduct facilitated, enzymatic kinetic resolution of 4-hydroxycyclopentenone and 4-hydroxycyclohexenone
O'Byrne, Aisling,Murray, Cian,Keegan, Dearbhla,Palacio, Carole,Evans, Paul,Morgan, Ben S.
supporting information; experimental part, p. 539 - 545 (2010/05/11)
The addition of 3,4-dimethoxybenzyl thiol 8, as a benzyl thiol surrogate, to racemic 4-hydroxycyclopent-2-enone 2 and 4-hydroxycyclohex-2-enone 15 gave the corresponding cis-adducts (±)-3-(3,4-dimethoxybenzylthio)-4- hydroxycyclopentanone 4b and (±)-3-(3,4-dimethoxybenzylthio)-4- hydroxycyclohexanone 16 with good diastereocontrol. In both cases, subsequent treatment with vinyl acetate, in the presence of a lipase enabled enantiomer resolution. Thus, (+)-16 and the acetate of its enantiomer, (-)-(1R,2S)-2-(3,4- dimethoxybenzylthio)-4-oxocyclohexyl acetate, (-)-17 were isolated in 98% enantiomeric excess. Based on the 1,4-dioxygenation pattern, (-)-17 can be used to prepare both enantiomers of 4-(tert-butyldimethylsilyloxy)cyclohex-2-enone 19. Firstly, saponification, with a sub-stoichiometric amount of NaOMe, followed by a one-pot silyl ether formation-sulfide elimination sequence gave (+)-19. Then using the same starting material a 6-step sequence, featuring a diastereoselective NaBH4 reduction and a Cope-type sulfoxide elimination, gave (-)-19.
Stereoselective total synthesis of (+)-varitriol
Srinivas,Sridhar,Rao, K. Rama
body text, p. 8527 - 8535 (2010/11/18)
Stereoselective total synthesis of (+)-varitriol, an antitumor natural product, was accomplished by two versatile strategies starting from the commercially available d-(-)-ribose and ethyl (S)-lactate. The key steps involved in the synthesis of the target molecule are epoxidation, cyclization, dihydroxylation and Diels-Alder reaction.
Ammonia-free Birch reductions with sodium stabilized in silica gel, Na-SG(I)
Costanzo, Michael J.,Patel, Mitul N.,Petersen, Kathryn A.,Vogt, Paul F.
supporting information; experimental part, p. 5463 - 5466 (2010/01/11)
Ammonia-free Birch reduction conditions were developed based upon sodium stabilized in silica gel for a variety of substrates. In general, the yields were similar to those reported for lump sodium in liquid ammonia.
Preparation of 1-Alkoxy-1,3-cyclohexadienes via Iron Complexation/Decomplexation
Rennels, Roger A.,McClusky, John V.
, p. 651 - 656 (2007/10/03)
A synthetic method for the preparation of 1-alkoxy-1,3-cyclohexadienes is presented. Iron complexation/decomplexation is used to produce and purify the desired compound without contamination of isomeric by products.
Reductions with lithium in low molecular weight amines and ethylenediamine
Garst,Dolby,Esfandiari,Fedoruk,Chamberlain,Avey
, p. 7098 - 7104 (2007/10/03)
Reductions of several types of compounds with lithium and ethylenediamine using low molecular weight amines as solvent are described. In all cases 1 mol of ethylenediamine or N,N'-dimethylethylenediamine per gram-atom of lithium was used. In some cases it was beneficial to add an alcohol as a proton donor. These reaction conditions were applied to the debenzylation of N-benzylamide and lactams which are refractory to hydrogenolysis with hydrogen and a catalyst. N-Benzylpilolactam 2, synthesized from pilocarpine hydrochloride in refluxing benzylamine, was debenzylated in good yield using 10 gram-atoms of lithium per mole (10 Li/mol) of 2 in n-propylamine. The debenzylation of N-benzyl-N-methyldecanoic acid amide, 4 (6 Li/mol), in t-butylamine/N,N'-dimethylethylenediamine gave N-methyldecanoic acid amide 6 in 70% yield. Alternatively, reduction of 4 (7 Li/mol) in t-butanol/n-propylamine/ethylenediamine gave n-decanal 12 in 36% yield. Using the same conditions, thioanisole, 1-adamantane-p-toluenesulfonamide, and 1-adamantane methyl p-toluenesulfonate were reduced with 3, 7, and 7.2 Li/mol of compound to give thiophenol (74%), adamantamine (91%), and 1-adamantane methanol (75%), respectively. In this solvent system naphthalene and 3-methyl-2-cyclohexene-1-one were reduced to isotetralin (74%) and 3-methyl cyclohexanone (quantitative) with 5 and 2.2 Li/mol of starting compound, respectively. Oximes and O-methyloximes were reduced to their corresponding amines using 5 and 8 Li/mol of compound, respectively. Anisole was also reduced to 1-methoxy-1,4-cyclohexadiene with 2.5 Li/mol of anisole. Undecanenitrile was reduced to undecylamine with 8.6 Li/mol. Additionally, a base-catalyzed formation of imidazolines from a nitrile and ethylenediamine was also explored.
Synthesis based on cyclohexadienes: Part 101 synthesis of 5,5'-dimethyl-7-methoxy-4-oxatricyclo[4.3.1.03,7]decan-2-ones
Raghavan,Subba Rao
, p. 2599 - 2616 (2007/10/02)
Synthesis of 5,5-dimethyl-7-methoxy-4-oxatricyclo[4,3,1,03,7]-decan-2-one 3a, a novel heterocyclic ring system present in morellin 1, and its 3-substituted derivatives 3b-e, is described from the Diels-Alder adducts 7, available from 1-methoxycyclohexa-1,4-dienes 4. Two routes, which involved the halocyclisation and the oxidative addition, were investigated for the conversion of the adducts 7 into 3. While the halocyclisation method resulted in mixtures, excellent yields of the target molecule were obtained by the second method. Solvolysis of the bromoether 9 resulted in a mixture of rearrangement products 10, 13, 15 and 16.
