69685-64-9Relevant articles and documents
Kinetic Resolution of 5-Substituted Cyclohexenols by Palladium-Catalyzed Asymmetric Redox-Relay Heck Reaction
Li, Hao,Gao, Ang,Liu, Xiu-Yan,Ding, Chang-Hua,Xu, Bin,Hou, Xue-Long
, p. 159 - 166 (2016/12/24)
The kinetic resolution of 2-substituted-cyclohexenols via palladium-catalyzed asymmetric redox-relay Heck reaction was realized, providing optically active 2-substituted cyclohexenols and trans-3,5-disubstituted cyclohexan-1-ones in high yield and good en
New insights into the mechanism of palladium-catalyzed allylic amination
Watson, Iain D. G.,Yudin, Andrei K.
, p. 17516 - 17529 (2007/10/03)
A comparative investigation into palladium-catalyzed allylic amination of unsubstituted aziridines and secondary amines has been carried out. The use of NH aziridines as nucleophiles favors formation of valuable branched products in the case of aliphatic allyl acetates. The regioselectivity of this reaction is opposite to that observed when other amines are used as nucleophiles. Our study provides evidence for the palladium-catalyzed isomerization of the branched (kinetic) product formed with common secondary amines into the thermodynamic (linear) product. In contrast, the branched allyl products obtained from unsubstituted aziridines do not undergo the isomerization process. Crossover experiments indicate that the isomerization of branched allylamines is bimolecular and is catalyzed by Pd0. The reaction has significant solvent effect, giving the highest branched-to-linear ratios in THF. This finding can be explained by invoking the intermediacy of σ-complexes, which is consistent with NMR data. The apparent stability of branched allyl aziridines towards palladium-catalyzed isomerization is attributed to a combination of factors that stem from a higher degree of s-character of the aziridine nitrogen compared to other amines. The reaction allows for regio- and enantioselective incorporation of aziridine rings into appropriately functionalized building blocks. The resulting methodology addresses an important issue of forming quaternary carbon centers next to nitrogen. The new insights into the mechanism of palladium-catalyzed allylic amination obtained in this study should facilitate synthesis of complex heterocycles, design of new ligands to control branched-to-linear ratio, as well as absolute stereochemistry of allylamines.
Mitsunobu Reaction of Unbiased Cyclic Allylic Alcohols
Shull, Brian K.,Sakai, Takashi,Nichols, Jeffrey B.,Koreeda, Masato
, p. 8294 - 8303 (2007/10/03)
The stereochemical inversion of unbiased allylic alcohols using triphenylphosphine, diethyl azodicarboxylate, and benzoic acid, commonly known as the Mitsunobu reaction, was studied in three different solvents with specific attention toward the product composition. The results generated for the Mitsunobu reaction of (R)-3-deuterio-2-cyclohexen-1-ol and the cis and trans isomers of 1-deuterio-5-methyl-2-cyclohexen-1-ol, 1-deuterio-5-tert-butyl-2-cyclohexen-1-ol, and optically active cis and trans 5-isopropyl-2-methyl-2-cyclohexen-1-ol all gave similar product distributions with respect to inversion and retention at the carbinol center as well-as syn and anti Sn2′ type addition when THF or benzene was used as the solvent (CH2Cl2 gave less selective product distributions). Interestingly, it was found that the quasi-equatorial and quasi-axial nature of the starting allylic alcohol does not appear to affect the product distribution for this reaction, nor does methyl substitution at the central carbon of the allylic alcohol. In all cases, significant amounts (8-28%) of non-SN2 type products were detected for these sterically unbiased allylic alcohols; only 72-77% of the product was from SN2 type reaction when sterically undemanding (R)-S-deuterio-2-cyclohexen-1-ol was subjected to Mitsunobu conditions.
A Regioselective and Stereospecific Synthesis of Allylsilanes from Secondary Allylic Alcohol Derivatives
Fleming, Ian,Higgins, Dick,Lawrence, Nicholas J.,Thomas, Andrew P.
, p. 3331 - 3350 (2007/10/02)
Primary and secondary allylic acetates and benzoates react with the dimethyl(phenyl)silyl-cuprate reagent to give allylsilanes, provided that the THF in which the cuprate is prepared is diluted with ether before addition of the allylic ester.The reaction is reasonably regioselective in some cases: (i) when the allylic system is more-substituted at one end than the other, as in the reactions 4->5 and 9->10; (ii) when the steric hindrance at one end is neopentyl-like, as in the reactions 15->16; and (iii) when the disubstituted double bond has the Z configuration, as in th e reactions Z-19->E-21 or, better, because the silyl group is becoming attached to the less-sterically hindered end of the allylic system, Z-20->E-22.The regioselectivity is better if a phenyl carbamate is used in place of the ester, and a three-step protocol assembling the mixed cuprate on the leaving group is used, as in the reactions 23->24 and E- or Z-29->E-21, or, best of all, because the silyl group is again becoming attached to the less-sterically hindered end of the allylic system, E- or Z-30->E-22.This sequence works well to move the silyl group onto the more substituted end of an allyl system, but only when the move is from a secondary allylic carbamate to a tertiary allylsilane, as in the reaction 38->39.Allyl(trimethyl)silanes can be made using alkyl- or aryl-cuprates on trimethylsilyl-containing allylic esters and carbamates, as in the reactions 40->41, and 43->44.The reaction of the silyl-cuprate with allylic esters and the three-step sequence with the allylic carbamates are stereochemically complementary, the former being stereospecifically anti and the latter stereospecifically syn.Homochiral allylsilanes can be ma de by these methods with high levels of stereospecificity, as shown by the synthesis of the allylsilanes 54, 58 and 59.
Synthesis of Homoallylic Alcohols from Allylic Phosphates and Aldehydes with Organoaluminum Reagent Containing Al-Sn Linkage
Matsubara, Seijiro,Wakamatsu, Kuni,Morizawa, Yoshitomi,Tsuboniwa, Noriyuki,Oshima, Koichiro,Nozaki, Hitosi
, p. 1196 - 1199 (2007/10/02)
Treatment of allylic phosphates with the reagent prepared from n-Bu3SnLi and Et2AlCl or from SnF2 and Et2AlCl affords allyltin compounds which react with aldehydes to produce homoallylic alcohols in good yields.The formation of allyltin compounds requires the catalytic amount of Pd(PPh3)4 and proceeds with inversion of the stereochemistry predominantly.
REGIO- AND STEREO-CHEMISTRY IN ALLYLATION OF ARYL GRINARD REAGENTS CATALYZED BY PHOSPHINE-NICKEL AND -PALLADIUM COMPLEXES
Hayashi, Tamio,Konishi, Mitsuo,Yokota, Kan-Ichi,Kumada, Makoto
, p. 359 - 374 (2007/10/02)
Nickel and palladium complexes with the 1,1'-bis(diphenylphosphino)ferrocene ligand effectively catalyze regioselective cross-coupling of allylic ethers such as 1- or 3-methyl-2-propenyl silyl ethers with aryl-Grinard reagents, where the nickel catalyst l
Alkylation of Allylic Derivatives. 8. Regio- and Stereochemistry of Alkylation of Allylic Carboxylates with Lithium Methylcyanocuprate
Goering, Harlan L.,Kantner, Steven S.
, p. 422 - 426 (2007/10/02)
Alkylation of 5-methyl-2-cyclohexenyl acetate (1-OAc) with lithium methylcyanocuprate (LiCu(CN)Me) is regiospecific (>90 percent excess γ-alkylation) and sterospecific (>95 percent anti alkylation).In the bicyclooct-3-en-2-yl system (3), alkylation is stereoselective (both isomers give exo alkylation) and regiospecific (excess γ-alkylation).Alkylation of trans-α-methyl-γ-mesitylallyl acetate (8-OAc) with LiCu(CN)Me gives 57 percent α- and 43 percent γ-alkylation as compared to >97 percent α-alkylation with LiCuMe2.Mechanistic implications are discussed.
Synthetic Applications of Phenylselenenyl Chloride Additions. A Simple 1,3-Enone Transposition Sequence
Liotta, Dennis,Zima, George
, p. 2551 - 2553 (2007/10/02)
The regiospecific addition of phenylselenenyl chloride to allylic alcohols is used as the key step in a simple 1,3-enone transposition sequence.
