Thiosquaramide-catalysed asymmetric double Michael addition of 2-(3H)-furanones to nitroolefines

2019 ◽  
Vol 17 (11) ◽  
pp. 2883-2886 ◽  
Author(s):  
Mengchen Yang ◽  
Chen Chen ◽  
Xing Yi ◽  
Yuan Li ◽  
Xiaoqin Wu ◽  
...  
Keyword(s):  
Michael Addition ◽  
Mild Conditions ◽  
Stereogenic Center

2,2,4-Trisubstituted butenolides bearing a quaternary stereogenic center were smoothly constructed with excellent stereoselectivities under mild conditions.

Regioselective 1,4-conjugate aza-Michael addition of dienones with benzotriazole

2017 ◽  
Vol 23 (4) ◽  
Author(s):  
Zheng Li ◽  
Tianpeng Li ◽  
Rugang Fu ◽  
Jingya Yang
Keyword(s):  
Transition Metal ◽  
Michael Addition ◽  
Potassium Acetate ◽  
High Yield ◽  
Metal Free ◽  
Mild Conditions

AbstractThe regioselective 1,4-conjugate aza-Michael addition of dienones with benzotriazole catalyzed by potassium acetate is described. A series of 3-(benzotriazol-1-yl)-1,5-diarylpent-4-en-1-ones were efficiently synthesized under mild conditions. This protocol has advantages of transition-metal free catalyst, high yield and high regioselectivity.

Sequential Michael addition/retro-Claisen condensation of aromatic β-diketones with α,β-unsaturated esters: an approach to obtain 1,5-ketoesters

2016 ◽  
Vol 14 (8) ◽  
pp. 2390-2394 ◽  
Author(s):  
Gui-Xin Cai ◽  
Jing Wen ◽  
Ting-Ting Lai ◽  
Dan Xie ◽  
Cheng-He Zhou
Keyword(s):  
Michael Addition ◽  
Bond Formation ◽  
One Pot ◽  
Claisen Condensation ◽  
Unsaturated Esters ◽  
Mild Conditions

A K2CO3-catalyzed one-pot protocol involving sequential C–C bond formation and cleavage of aromatic β-diketones with α,β-unsaturated esters is developed to obtain 1,5-ketoesters, proceeding smoothly under mild conditions in up to 98% isolated yield.

Facile Access to 1,5-Benzodiazepines via Amine-Promoted (4+3) Annulations of δ-Acetoxy Allenoates with o-Diaminobenzenes under Mild Conditions

Synlett ◽  
2018 ◽  
Vol 29 (09) ◽  
pp. 1176-1180 ◽  
Author(s):  
Yi-Fan Wang ◽  
Cheng-Yu He ◽  
Longlei Hou ◽  
Ping Tian ◽  
Guo-Qiang Lin ◽  
...  
Keyword(s):  
Michael Addition ◽  
Cascade Reaction ◽  
Acetate Group ◽  
Mild Conditions

An amine-promoted (4+3) annulation of δ-acetoxy allenoate with o-diaminobenzene is reported, providing a facile access to 1,5-benzodiazepine. This method features wide reaction scope, mild conditions, and readily available starting materials. The cascade reaction involves aza-Michael addition of o-diaminobenzene to allenoate, elimination of acetate group, and subsequent 1,6-aza-Michael addition.

Highly Enantioselective Michael Addition of Dithiomalonates to Nitroolefins Catalyzed by New Bifunctional Chiral Thioureas

Synthesis ◽  
2018 ◽  
Vol 50 (13) ◽  
pp. 2577-2586 ◽  
Author(s):  
Jia-Ni Yuan ◽  
Hui-Xia Liu ◽  
Qin-Qin Tian ◽  
Nan Ji ◽  
Kuo Shen ◽  
...  
Keyword(s):  
Michael Addition ◽  
Mild Conditions ◽  
Highly Efficient ◽  
Michael Adducts ◽  
Asymmetric Michael Addition ◽  
High Yields

We report a highly efficient asymmetric Michael addition of dithiomalonates to trans-β-nitroolefins catalyzed by versatile cinchona-based bifunctional thioureas, which provides the corresponding adducts in high yields (up to 92%) and with excellent enantioselectivities (up to 99% ee) under mild conditions. Replacement of the catalyst with its pseudo-enantiomer gives the Michael adducts with opposite configuration in similar yields and enantioselectivities.

NHC-catalyzed oxidative cyclization reaction for the synthesis of 3-substituted phthalides

2014 ◽  
Vol 12 (15) ◽  
pp. 2388-2393 ◽  
Author(s):  
So Won Youn ◽  
Hyoung Sub Song ◽  
Jong Hyub Park
Keyword(s):  
Michael Addition ◽  
Functional Group ◽  
Addition Reaction ◽  
Oxidative Cyclization ◽  
Cyclization Reaction ◽  
Michael Addition Reaction ◽  
Stereogenic Center

An efficient NHC-catalyzed domino oxidation/oxa-Michael addition reaction of 2-alkenylbenzaldehydes has been developed to afford 3-substituted phthalides bearing a C3-stereogenic center with a broad substrate scope and wide functional group tolerance.

scholarly journals The synthesis of chiral β-naphthyl-β-sulfanyl ketones via enantioselective sulfa-Michael reaction in the presence of a bifunctional cinchona/sulfonamide organocatalyst

2021 ◽  
Vol 17 ◽  
pp. 494-503
Author(s):  
Deniz Tözendemir ◽  
Cihangir Tanyeli
Keyword(s):  
Michael Addition ◽  
Michael Reaction ◽  
Cinchona Alkaloid ◽  
Catalyst Loading ◽  
Asymmetric Transformations ◽  
Chalcone Derivatives ◽  
Mild Conditions ◽  
Michael Adducts

Cinchona alkaloid-derived organocatalysts are widely employed in various asymmetric transformations, yielding products with high enantiopurity. In this respect, a bifunctional quinine-derived sulfonamide organocatalyst was developed to catalyze the asymmetric sulfa-Michael reaction of naphthalene-1-thiol with trans-chalcone derivatives. The target sulfa-Michael adducts were obtained with up to 96% ee under mild conditions and with a low (1 mol %) catalyst loading. Selected enantiomerically enriched sulfa-Michael addition products were subjected to oxidation to obtain the corresponding sulfones.

scholarly journals Regiospecific 1,4-Michael Addition of Phenylacetonitrile to 1,5-Diarylpenta-2,4-Dien-1-Ones

2018 ◽  
Vol 42 (7) ◽  
pp. 347-349
Author(s):  
Zheng Li ◽  
Wenli Song
Keyword(s):  
Michael Addition ◽  
High Selectivity ◽  
Mild Conditions ◽  
High Yields

The regiospecific 1,4-Michael addition of phenylacetonitrile to (2E,4E)-1,5-diarylpenta-2,4-dien-1-ones produced 12 novel (E)-3-(2-oxo-2-arylethyl)-2,5-diarylpent-4-enenitriles in 77-88% yield. The advantages of the method are broad substrate scope, mild conditions, good to high yields and high selectivity. The method can also be extended to a gram scale.

The Thomson Synthesis of (–)-GB17

2015 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Michael Addition ◽  
Physiological Activity ◽  
Addition Product ◽  
Systematic Investigation ◽  
Unsaturated Ester ◽  
Wide Range ◽  
Stereogenic Centers ◽  
Northwestern University ◽  
Convergent Assembly ◽  
Stereogenic Center

(–)-GB17 3 is one of the Galbulimima alkaloids, a family that shows a wide range of interesting physiological activity. Regan J. Thomson of Northwestern University devised (Angew. Chem. Int. Ed. 2012, 51, 2481) a convergent assembly of 3, a key step of which was the intramolecular Michael cyclization of 1 to 2. The hydroxy aldehyde 6 was prepared by alkylation of the dithiane 4 with 5, followed by hydrolysis. The preparation of 9, by condensation of 8 with 7 followed by hydrogenation and protection, had been reported by Lhommet. Condensation of 9 with the linchpin reagent 10 gave an intermediate keto phosphonate, which was combined with 6 to give, after oxidation, the aldehyde 1. Two new stereogenic centers are created in the course of the cyclization of 1. The authors found that the TFA salt 11 of the Hayashi catalyst delivered 2 with high diastereocontrol. Control experiments showed that the buttressing effect of the dithiane was required for the cyclization. The authors then explored the next intramolecular Michael cyclization of 13 to 14. In this cyclization, the stereogenic center at 6 is in jeopardy by elimination and readdition. Cyclization of the trans unsaturated ester led to the wrong diastereomer of 14, but cyclization of the cis ester 13, prepared by the Still-Gennari protocol, cleanly gave the desired diastereomer. The reaction worked best with the free amine. Under the conditions of the reaction the Michael addition product spontaneously cyclized to the lactam 14. The ketone of 14 was selectively enolized, then converted to its enol triflate, which under Pd-mediated reduction gave the alkene 15. Alkylation of 15 with 16 predominantly gave the diene 18. Hydrolysis of the dithiane to the ketone followed by reduction gave mainly the desired equatorial alcohol, which was cleaved oxidatively to (–)-GB17 3. Although there have been many isolated reports of the utility of intramolecular Michael addition as a synthetic method, there has been little systematic investigation. The optimization studies that are the heart of this work are a welcome addition.

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