58498-93-4Relevant academic research and scientific papers
Carbonylative, Catalytic Deoxygenation of 2,3-Disubstituted Epoxides with Inversion of Stereochemistry: An Alternative Alkene Isomerization Method
Lamb, Jessica R.,Hubbell, Aran K.,MacMillan, Samantha N.,Coates, Geoffrey W.
supporting information, p. 8029 - 8035 (2020/05/01)
Reactions facilitating inversion of alkene stereochemistry are rare, sought-after transformations in the field of modern organic synthesis. Although a number of isomerization reactions exist, most methods require specific, highly activated substrates to achieve appreciable conversion without side product formation. Motivated by stereoinvertive epoxide carbonylation reactions, we developed a two-step epoxidation/deoxygenation process that results in overall inversion of alkene stereochemistry. Unlike most deoxygenation systems, carbon monoxide was used as the terminal reductant, preventing difficult postreaction separations, given the gaseous nature of the resulting carbon dioxide byproduct. Various alkyl-substituted cis- A nd trans-epoxides can be reduced to trans- A nd cis-alkenes, respectively, in >99:1 stereospecificity and up to 95% yield, providing an alternative to traditional, direct isomerization approaches.
An alkylidene carbene C-H activation approach toward the enantioselective syntheses of spirolactams: Application to the synthesis of (-)-adalinine
Annadi, Krishna,Wee, Andrew G. H.
, p. 1021 - 1038 (2016/02/19)
A method based on in situ alkylidene carbene generation-C-H insertion reaction of 5-(3-oxobutyl)pyrrolidin-2-ones and 6-(3-oxobutyl)piperidin-2-ones is developed for the enantioselective synthesis of 1-azaspiro[4,4]non-6-ene-2-ones and 6-azaspiro[4,5]dec-1-ene-7-ones. The required 5-(3-oxobutyl)pyrrolidin-2-ones and 6-(3-oxobutyl)piperidin-2-ones are prepared from the Wacker oxidation of internal alkenes typified by 5-(but-2-enyl)pyrrolidin-2-ones and 6-(but-2-enyl)piperidin-2-ones, respectively. Excellent regioselectivity (≥92:8) is realized for the Wacker oxidation, and high yields (78-89%) of the desired lactam ketones are obtained. The results from further investigations into the Wacker oxidation suggested that the high regioselectivity of the oxidation in these lactam alkenes might be due to the participation of the lactam nitrogen via intramolecular coordination to Pd(II) during the reaction. Studies on alkylidene carbene generation-C-H insertion reaction of the lactam ketones revealed that the reaction efficiency is sensitive to the reaction temperature and the amount of lithio(trimethylsilyl)diazomethane employed, which led to the development of optimal reaction conditions for effecting alkylidene carbene generation-C-H insertion. Using the optimal reaction conditions, good to high yields (53-76%) of both γ- and δ-lactam spirocycles were obtained. The synthetic utility of the spirolactams was demonstrated by the synthesis of (-)-adalinine.
Carbonylation of cis-disubstituted epoxides to trans-β-lactones: Catalysts displaying steric and contrasteric regioselectivity
Mulzer, Michael,Coates, Geoffrey W.
supporting information, p. 11851 - 11862 (2015/02/05)
trans-β-Lactones are a versatile and useful class of compounds, but reliable methods for their direct synthesis are still limited. Addressing this problem, we present herein two catalysts for the regioselective carbonylation of cis-disubstituted epoxides. The two catalysts show high activities and opposing regioselectivities so that either one of the two possible β-lactone regioisomers can be obtained selectively.
Cobalt-catalyzed reductive allylation of alkyl halides with allylic acetates or carbonates
Qian, Xin,Auffrant, Audrey,Felouat, Abdellah,Gosmini, Corinne
supporting information; experimental part, p. 10402 - 10405 (2011/12/03)
An efficient method for the direct allylation of alkyl halides catalyzed by simple cobalt(II) bromide has been developed. This reaction, using a variety of substituted allylic acetates or carbonates, provides the linear product as the major product. It displays broad substrate scope and good functional group tolerance. Copyright
Copper catalyzed magnesium-Barbier reaction for γ-selective alkyl-allyl coupling
Erdik, Ender,Ko?o?lu, Melike
, p. 4211 - 4214 (2008/02/08)
CuCN catalyzed alkyl-allyl coupling under magnesium-Barbier conditions occurs regioselectively and affords predominantly the γ-products in good to high yields. This one-pot CuCN catalyzed reaction utilising Mg, an alkyl halide and an allylic substrate in THF at room temperature provides an easy alternative to the classical CuCN catalyzed γ-allylation of alkyl Grignard reagents.
AN EASY SYNTHESIS OF THE 2-PHENYLSULFONYL-SUBSTITUTED ALLYLIC BROMIDES AND ACETATES AND THEIR REACTIVITY TOWARDS NUCLEOPHILES
Auvray, P.,Knochel, P.,Normant, J. F.
, p. 5095 - 5098 (2007/10/02)
The reaction of phenyl vinyl sulfone with various aldehydes in the presence of a catalytic amount of DABCO furnishes in good yields the corresponding 2-phenylsulfonyl-substituted alcohols 5a-5e which can be easily converted into their acetates 2a-2b or into their allylically rearranged bromides 3a-3d.These reagents, in turn, react with nucleophiles (ketone enolates and cuprates) with an allylic rearrangement (SN2' mechanism) to give the functionalized unsaturated sulfones 6a-g and 7a-g.A palladium catalyzed reaction allows a stereo-controlled transformation of the sulfone 6b into the (Z,Z) skipped 1,4-diene 8.
