Oxidative thiocyanation of allylic alcohols: an easy access to allylic thiocyanate within K2S2O8 and NH4SCN

2022 ◽  
Author(s):  
Keyuan Zhang ◽  
Tianbing Liang ◽  
Yulong Wang ◽  
Chonglong He ◽  
Mingyou Hu ◽  
...  
Keyword(s):  
Practical Method ◽  
Allylic Alcohol ◽  
Easy Access ◽  
Allylic Alcohols ◽  
Leaving Group

A practical method for the synthesis of allylic thioacyanate from allylic alcohol was disclosed employing K2S2O8 as the oxidant and NH4SCN as the thiocyanate source. Without introducing a leaving group...

Cyanoalkylation/alkynylation of allylic alcohol through intramolecular radical 1,2-alkynyl migration

2021 ◽  
Vol 19 (11) ◽  
pp. 2416-2419
Author(s):  
Shengnan Jin ◽  
Fan Chen ◽  
Pengcheng Qian ◽  
Jiang Cheng
Keyword(s):  
Allylic Alcohol ◽  
Allylic Alcohols ◽  
Butyl Peroxide

A di-tert-butyl peroxide (DTBP)-promoted difunctionalization of α-aryl α-alkynyl allylic alcohols with alkyl nitriles was developed, affording a series of α-alkynyl γ-cyano functionalized ketones in moderate yields.

Stereoselectivity of directed epoxidations of 22-hydroxy-Δ23-sterol side chains

1996 ◽  
Vol 74 (10) ◽  
pp. 1857-1867 ◽  
Author(s):  
Thomas G. Back ◽  
Denise L. Baron
Keyword(s):  
Molecular Modeling ◽  
Parent Compound ◽  
Allylic Alcohol ◽  
Allylic Alcohols ◽  
Methyl Groups ◽  
Side Chains ◽  
Molybdenum Hexacarbonyl ◽  
Reliable Prediction ◽  
Tert Butyl Hydroperoxide ◽  
Threo Isomer

A series of 22-hydroxy-Δ23-sterols comprising (3β,5α,6β,22S)-6-methoxy-3,5-cyclo-25,26,27-trinorcholest-23-en-22-ol (6), (3β,5α,6β,22S,23E)-6-methoxy-3,5-cyclo-26,27-dinorcholest-23-en-22-ol (7), 3β,5α,6β,22R)-6-methoxy-23-methyl-3,5-cyclo-25,26,27-trinorcholest-23-en-22-ol(10),3β,5α,6β,22S,23Z)-6-methoxy-3,5-cyclo-26,27-dinorcholest-23-en-22-ol (11), and 3β,5α,6β,22R)-6-methoxy-3,5-cyclo-26,27-dinorergost-23-en-22-ol (12) were subjected to epoxidation with m-chloroperbenzoic acid and tert-butyl hydroperoxide in the presence of either vanadyl acetoacetonate or molybdenum hexacarbonyl, and the threo:erythro ratios of the products were determined. The results are of relevance for the synthesis of sterols with oxygenated side chains, such as brassinolide (1). The oxidations of 6 and 7 were erythro selective with all three oxidants, especially with the vanadium-catalyzed system. Peracid oxidation of the 22-tert-butyldimethylsilyl ether (8) and 22-pivaloate (9) of alcohol 7 showed similar erythro selectivity to that of the parent compound 7. Allylic alcohol 10 gave exclusively the erythro epoxide with all three oxidants, while 11 and 12 were threo-selective under all three conditions. Molecular modeling indicated that erythro selectivity in the vanadium-catalyzed epoxidation of 10 was consistent with a destabilizing interaction (A(1,2) strain) between the gem-methyl and C(21) methyl groups in the conformation required for formation of the threo-isomer. The threo-selective peracid oxidations of 11 and 12 were attributed to A(1,3) strain between the cis-methyl groups and C(20) in the conformation required for formation of the erythro-epoxide. The differences in the calculated energies of conformations leading to the threo- and erythro epoxide diastereomers of substrates containing no gem or cis substituents proved too small to permit reliable prediction of diastereoselectivity. Key words: 22-hydroxy-Δ23-sterols, brassinosteroids, allylic alcohols, epoxidation, diastereoselectivity

The Nakada Synthesis of (-)-FR182877

2013 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Complex Mixture ◽  
Alder Reaction ◽  
Single Step ◽  
Diels Alder ◽  
Allylic Alcohol ◽  
Allylic Alcohols ◽  
Weinreb Amide ◽  
Diels Alder Reaction ◽  
Reaction Matrix ◽  
Stereogenic Centers

The Streptomyces metabolite (-)-FR182877 3 binds to and stabilizes microtubules, showing the same potency of anticancer activity as Taxol (paclitaxel). Masahisa Nakada of Waseda University assembled (Angew. Chem. Int. Ed. 2009, 48, 2580) the hexacyclic ring system of 3 by the tandem intramolecular Diels-Alder–intramolecular hetero Diels-Alder cyclization of 1, generating seven new stereogenic centers in a single step. The construction of the pentaene substrate 1 started with the known aldehyde 4, prepared by homologation of commercial ethyl 3-methyl-4-oxocrotonate. Addition of the propionyl oxazolidine anion 5 proceeded with high diastereocontrol, to give 6. The acyl oxazolidinone was not an efficient acylating agent, so it was converted to the Weinreb amide. Protection and deprotection then delivered the allylic acetate 7. The key step in the pentaene assembly was the carefully optimized Negishi-Wipf methylation of 8, followed by Pd-mediated coupling of the alkenyl organometallic so generated with the allylic acetate, to give 9. Condensation of the derived keto phosphonate 11 with the known aldehyde 12 then delivered the enone 13. The Nakada group has worked extensively on the intramolecular Diels-Alder reaction of substrates such as 1. They have shown that protected anti diols such as 1 cyclize with substantial diastereocontrol and in the desired sense. In contrast, cyclizations of protected syn diols proceed with poor diastereocontrol. The enone 13 was therefore reduced to the anti diol and protected, leading to 14 . Oxidation of 14 at room temperature led to a complex mixture, but slow oxidation at elevated temperature delivered 2 . Although the yield of 2 was not much better than if the reactions were carried out sequentially, first the intramolecular Diels-Alder cyclization, then the intramolecular hetero Diels-Alder cyclization, with the cascade protocol pure 2 was more readily separated from the reaction matrix. With 2 in hand, there was still the challenge of assembling the seven-membered ring. Cyclization was effected with an intramolecular Heck protocol. The two diastereomers of the allylic alcohol 15 cyclized with comparable efficiency. Ir-catalyzed alkene migration then converted the allylic alcohols to a mixture of ketones, which was equilibrated to give the more stable diasteromer.

Hydride Reductions of 1-Phenyl-1-nonen-3 -one: Mass Spectrometry of 1-Phenyl-1-nonen-3-ols and Relative Stereochemistry of the Diastereoisomeric 4-Dimethylaminomethyl-1-Phenyl-1-nonen-3-ols

1974 ◽  
Vol 52 (13) ◽  
pp. 2522-2530 ◽  
Author(s):  
Wesley Gordon Taylor ◽  
Jonathan Richard Dimmock
Keyword(s):  
Aluminum Hydride ◽  
Addition Product ◽  
Mannich Bases ◽  
Allylic Alcohol ◽  
Lithium Aluminum ◽  
Allylic Alcohols ◽  
Carbonyl Carbon Atom ◽  
Methyl Radical ◽  
Mass Spectral ◽  
Relative Stereochemistry

The metal hydride reduction products of some styryl ketones and dimethylaminomethyl Mannich bases have been investigated. Sodium borohydride selectively attacked the carbonyl carbon atom to give the desired allylic alcohols. Reduction of 1-phenyl-1-nonen-3-one with lithium aluminum hydride gave 1-phenyl-3-nonanol which represents the conjugate addition product. Fragmentations of 1-phenyl-1-nonen-3-ol were compared to the modes of mass spectral breakdown of 4-phenyl-3-buten-2-ol, an allylic alcohol which is known to behave like a saturated ketone on electron bombardment. Peaks corresponding to the McLafferty ion and the loss of a methyl radical from this rearrangement product were observed. Certain Mannich bases were reduced to diastereoisomeric allylic amino alcohols. The separation, 1H n.m.r. spectroscopy, and relative stereochemistry of the diastereoisomers are discussed.

scholarly journals Pd-Catalyzed Cyclocarbonylation of Allylic Alcohol under Benign Conditions with Ionic Liquid as Stabilizer

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2093
Author(s):  
Nasrin Nemati ◽  
Reza Eslamloueyan ◽  
Amalie Modvig ◽  
Anders Riisager
Keyword(s):  
Ionic Liquid ◽  
Catalyst System ◽  
Allylic Alcohol ◽  
Allylic Alcohols ◽  
Optimal Conditions ◽  
Consecutive Reactions ◽  
Partial Pressures ◽  
Palladium Catalyzed ◽  
First Time ◽  
Time Of Reaction

Homogeneous palladium-catalyzed (Pd-catalyzed) cyclocarbonylation of unsaturated allylic alcohols and alkynols in the presence of hydrogen forms lactone products with important applications in the food, perfume, and polymer industry. In this work, the cyclocarbonylation of 2-methyl-3-buten-2-ol was studied for the first time using a very active Pd-DPEphos (bis[(2-diphenylphosphino)phenyl]ether) catalyst in the presence of the ionic liquid (IL) [BMIM]Cl (1-butyl-3-methylimidazolium chloride) in dichloromethane to selectively produce 4,4-dimethyl-γ-butyrolactone. The effect of different parameters such as temperature, gas partial pressures, time of reaction, substrate and ligand concentrations were investigated and found to provide optimal conditions for lactonization (95 °C, 28 bar (CO/H2/N2: 20/5/3)), 18 h, 0.1 M substrate, and 16 mol% DPEphos), which were significantly milder than previously reported systems for cyclocarbonylation. Importantly, the study further showed that presence of the IL in the reaction mixture provided stabilization of the catalyst system and prevented formation of Pd-black, which allowed reuse of the catalytic system in consecutive reactions after intermediate extraction of the lactone product.

scholarly journals Diastereoselective addition of alkenylchromium(III) reagents to Garner’s aldehyde: Nozaki-Hiyama-Kishi coupling approach to sphingosines and ceramides

2014 ◽  
Vol 79 (6) ◽  
pp. 627-636 ◽  
Author(s):  
Zorana Ferjancic ◽  
Radomir Matovic ◽  
Filip Bihelovic
Keyword(s):  
Hydrophobic Interactions ◽  
Easy Access ◽  
Allylic Alcohols ◽  
Protecting Group ◽  
Carbon Chains ◽  
Diastereoselective Addition ◽  
Coupling Approach

The intermolecular Nozaki-Hiyama-Kishi coupling between alkenylchromium(III) reagents, derived from either (E)-2-bromostyrene or (E)-1-iodopentadec-1-ene, and conformationally rigid Garner's aldehyde resulted in stereoselective formation of Felkin-type allylic alcohols in good yields, thus providing an easy access to sphingosines. In addition, when the protecting group in Garner's aldehyde was changed (from Boc to N-octanoyl), a reversal of stereoselectivity was observed in the reaction with (E)-pentadec-1-enylchromium(III), probably as a result of hydrophobic interactions between long carbon chains of the reaction partners.

Synthesis of orotidine by intramolecular nucleosidation

2015 ◽  
Vol 51 (26) ◽  
pp. 5618-5621 ◽  
Author(s):  
E.-K. Kim ◽  
R. Krishnamurthy
Keyword(s):  
Easy Access ◽  
Leaving Group ◽  
High Yields

An intramolecular nucleosidation approach, using orotate as a leaving group, provides easy access to orotidine in high yields.

Carbon dioxide-promoted palladium-catalyzed dehydration of primary allylic alcohol: access to substituted 1,3-dienes

2020 ◽  
Author(s):  
Yan-Kai Huang ◽  
Wen-Zhen Zhang ◽  
Ke Zhang ◽  
Wen-Le Wang ◽  
Xiaobing Lu
Keyword(s):  
Carbon Dioxide ◽  
Allylic Alcohol ◽  
Allylic Alcohols ◽  
Dehydration Reaction ◽  
Alcohol Access ◽  
Palladium Catalyzed

1,3-dienes are versatile synthons and important monomers. Herein we report a carbon dioxide promoted dehydration reaction of primary allylic alcohols to produce substituted 1,3-dienes in good yields. Taking advantage of...

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