33599-85-8Relevant academic research and scientific papers
Facile synthesis of(e)-4-aryl-2-methyl-3-butenoic acids and their methyl esters by the condensation of tiglic acid dianion with arynes
Tran, Long,Rakeb Deshmukh,Biehl, Ed
, p. 963 - 971 (1996)
The condensation of various arynes with tiglic acid dianion yields (E)-4-aryl-2-methyl-3-butenoic acids exclusively, after proton quench. These acids were characterized as their methyl esters, which were prepared by treating the acids with diazomethane.
Visible Light Induced Br?nsted Acid Assisted Pd-Catalyzed Alkyl Heck Reaction of Diazo Compounds and N-Tosylhydrazones
Dubrovina, Anastasiia,Gevorgyan, Vladimir,Kvasovs, Nikita,Zhang, Ziyan
supporting information, (2021/11/30)
A mild visible light-induced palladium-catalyzed alkyl Heck reaction of diazo compounds and N-tosylhydrazones is reported. A broad range of vinyl arenes and heteroarenes with high functional group tolerance, as well as a range of different diazo compounds, can efficiently undergo this transformation. This method features Br?nsted acid-assisted generation of hybrid palladium C(sp3)-centered radical intermediate, which allowed for new selective C?H functionalization protocol.
Ni-Catalyzed Reductive C-O Bond Arylation of Oxalates Derived from α-Hydroxy Esters with Aryl Halides
Gao, Mengyu,Sun, Deli,Gong, Hegui
supporting information, p. 1645 - 1648 (2019/03/11)
A Ni-catalyzed reductive cross-coupling of α-hydroxycarbonyl compounds modified with oxalyl groups and aryl halides has been developed that furnishes α-aryl esters under mild conditions and tolerates a variety of functionalized aryl halides bearing electron-withdrawing and -donating groups. This work highlights C-O bond fragmentation on secondary alkyl carbon centers that generates α-carbonyl radicals.
Arylation and vinylation of α-diazocarbonyl compounds with boroxines
Peng, Cheng,Zhang, Wei,Yan, Guobing,Wang, Jianbo
supporting information; experimental part, p. 1667 - 1670 (2009/08/07)
An alternative approach for α-arylation and α-vinylation of carbonyl compounds is described: reaction between aryl-or vinylboroxines with α-diazocarbonyl compounds leads to the formation of α-arylated or α-vinylated carbonyl compounds under mild conditions.
Nickel-catalyzed electrochemical couplings of vinyl halides: Synthetic and stereochemical aspects
Cannes,Condon,Durandetti,Perichon,Nedelec
, p. 4575 - 4583 (2007/10/03)
Homo- and cross-coupling involving alkenyl halides have been performed efficiently using an electroassisted nickel-complex catalysis. Valuable product such as conjugated dienes, β,γ- or γ,δunsaturated esters, ketones, or nitriles, as well as alkenylated aryl compounds are thus prepared with high yields and high stereoselectivity. Partial isomerization is only observed in a few cases, when the alkenyl halide is involved in a late step of the catalytic cycle. This is the case in the preparation of (Z,Z)-1,3-diene.
Total synthesis of cryptophycins via a chemoenzymatic approach
Salamonczyk, Grzegorz M.,Han, Kang,Guo, Zhi-Wei,Sih, Charles J.
, p. 6893 - 6900 (2007/10/03)
A highly convergent synthesis of cryptophycins in their enantiomerically-pure forms was achieved. Our strategy consists of the synthesis of the two units 3 and 4 and linking them together to form the macrocyclic ring. The upper unit 3 was prepared from 10 in four steps, and the lower unit 4 was prepared from 20 in three steps. Enantioselective biocatalytic methodology was used to prepare the requisite chiral building blocks, (R)-11 and (R)-19. The stereochemical versatility of this synthetic approach is demonstrated by the synthesis of cryptophycin A and the four diastereomers of cryptophycin C.
Lithium 3-Lithio-3-tosylalkanoates: β-Acylvinyl Anion Equivalents of β-Lithiated α,β-Unsaturated Carboxylic Acids
Bonete, Pedro,Najera, Carmen
, p. 3202 - 3209 (2007/10/02)
The dilithiation of β-tosylated propanoic, 2-methylpropanoic, and butanoic acid 10 with n-butyllithium at -78 deg C leads to the corresponding lithium 3-lithio-3-tosylalkanoates 11.They react with different electrophilic reagents (deuterium oxide, iodine, trimethylchlorosilane, alkyl halides, and acyl chlorides) to give the corresponding 3-substituted tosylated alkanoic acids 12.When carbonyl compounds are allowed to react with intermediates 11 followed by in situ lactonization with trifluoroacetic anhydride and base-promoted elimination α,β-butenolides are obtained.This methodology is applied to the direct synthesis of the rosefuran lactone precursor 14cg, the O-benzyl derivative of (+/-)-umbelactone (14ch), and (+/-)-andirolactone (14ci).The alkylation and acylation reactions of organolithium compounds 11 followed by esterification with hydrogen chloride in methanol and treatment with 1,8-diazabicycloundec-7-ene (DBU) afford α,β- and/or β,γ-unsaturated esters 17 and/or 18 and unsaturated 4-keto esters 19, respectively.The last methodology has been applied to the synthesis of the unsaturated 4-keto ester 19ae precursor of the seco acid of (+/-)-pyrenophorin (22).
Temperature-Dependent Alkylation of γ-Phenyl β,γ-Unsaturated Acid and Ester Systems in Hexamethylphosphortriamide-Tetrahydrofuran Solutions Using Lithium Diisopropylamide
Veen, Reinout H. van der,Cerfontain, Hans
, p. 342 - 346 (2007/10/02)
The reactivities of some β,γ-unsaturated carboxylic acids and their methyl esters toward alkylation with methyl iodide using the lithium diisopropylamide-hexamethylphosphortriamide (LDA-HMPT) systems in THF have been investigated.The methylation selectivity of pent-3-enoic acid (2) and (1,2-dihydro-3-naphtyl)acetic acid (6) on using 1.0 equiv. of methyl iodide is high, the α-mono- to α,α-dimethylation ratios at -78 deg C being >20.The selectivity is substantially lower for styrylacetic acid (4) and increases with increasing temperature from 2.3 at -78 deg C to 8.5 at -10 deg C.The occurrence of dimethylation is ascribed to intermolecular proton exchange between the monomethylated species IIa and the nonmethylated species Ia.For the β,γ-unsaturated esters the methylation selectivity is somewhat higher than that for the corresponding carboxylic acids.
PHOTOCHEMISTRY OF beta , gamma -ENONES. 7. 1 INTRAMOLECULAR COMPETITION BETWEEN DI- pi -METHANE AND OXA-DI- lambda -METHANE REARRANGEMENTS. ON THE INTERMEDIACY OF CHARGE- TRANSFER COMPLEXES AND ZWITTERIONS IN THE DI- pi -METHANE REARRANGEMENTS.
van der Veen,Kruk,Cerfontain
, p. 4367 - 4374 (2007/10/02)
The intramolecular competiton between the di- pi -methane (DPM) rearrangement and the oxa-di- pi -methane (ODPM) rearrangement of 3-(3,4-dihydro-2-naphthyl)-3-methylpent-4-en-2-one (1), (E)-3-methyl-3-vinyl-5-phenylpent-4-en-2-one (2), and 2-cyclopent-1enyl-2-vinylcyclopentanone (3) has been examined. Dienone 1 in benzene upon triplet photosenitization with 4-benzoylbiphenyl leads to the formation of one DPM isomer and two ODPM isomers in ratio of 35:17:10. The results are consistent with a stepwide mechanism via 1,4- and 1,3-biradicals as the subsequent intermediates. The occurrence of only one instead of the expected two DPM isomers is explained in terms of the specific charge-transfer complexation in the 1,3-biradical rotamer intermediate in which the phenylene and acetyl group are 'cisoid' (CTC).
