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1.
Nat Commun ; 12(1): 5881, 2021 Oct 07.
Article in English | MEDLINE | ID: mdl-34620857

ABSTRACT

Hydroalkylation, the direct addition of a C(sp3)-H bond across an olefin, is a desirable strategy to produce valuable, complex structural motifs in functional materials, pharmaceuticals, and natural products. Herein, we report a reliable method for accessing α-branched amines via nickel-catalyzed hydroalkylation reactions. Specifically, by using bis(cyclooctadiene)nickel (Ni(cod)2) together with a phosphine ligand, we achieved a formal C(sp3)-H bond insertion reaction between olefins and N-sulfonyl amines without the need for an external hydride source. The amine not only provides the alkyl motif but also delivers hydride to the olefin by means of a nickel-engaged ß-hydride elimination/reductive elimination process. This method provides a platform for constructing chiral α-branched amines by using a P-chiral ligand, demonstrating its potential utility in organic synthesis. Notably, a sulfonamidyl boronate complex formed in situ under basic conditions promotes ring-opening of the azanickellacycle reaction intermediate, leading to a significant improvement of the catalytic efficiency.

2.
Org Lett ; 21(18): 7635-7638, 2019 Sep 20.
Article in English | MEDLINE | ID: mdl-31507178

ABSTRACT

A diphenyl-diselenide-mediated Claisen-type rearrangement/cyclization of propargylic aryl ethers under metal-free conditions is developed, affording various naphthofuran-2-carboxaldehydes in moderate to excellent yield. The broad substrate scope and excellent functional group compatibility suggest that it can be a straightforward and powerful method to access naphthofuran-2-carboxaldehydes in a highly regioselective manner. Moreover, this reaction can be scaled up to the gram scale.

3.
Chem Sci ; 9(19): 4529-4534, 2018 May 21.
Article in English | MEDLINE | ID: mdl-29896396

ABSTRACT

Coupling reactions involving non-sulfonated C-O electrophiles provide a promising method for forming C-C bonds, but the incorporation of functionalized or secondary alkyl groups remains a challenge due to the requirement for well-defined alkylmetal species. In this study, we report a reductive nickel-catalyzed cross-coupling of benzyl oxalates with alkyl bromides, using oxalate as a new leaving group. A broad range of highly functionalized alkyl units (such as functional groups: alkyl chloride, alcohol, aldehyde, amine, amide, boronate ester, ether, ester, heterocycle, phosphonate, strained ring) were efficiently incorporated at the benzylic position. The utility of this synthetic method was further demonstrated by late-stage modification of complex bioactive compounds. Preliminary mechanistic experiments revealed that a radical process might be involved in the reaction.

4.
Org Biomol Chem ; 14(19): 4507-10, 2016 May 11.
Article in English | MEDLINE | ID: mdl-27097591

ABSTRACT

A silver-promoted oxidative cascade cyclization with a phosphorylation/1,5-aryl migration/desulfonylation/dearomatization process is presented here, providing an efficient method to synthesize azaspiro[4.5]decenones with high regioselectivity. The cinnamamidyl radical, which has rarely been reported before, plays a key role in this reaction.

5.
Org Lett ; 16(24): 6298-301, 2014 Dec 19.
Article in English | MEDLINE | ID: mdl-25423918

ABSTRACT

A novel iron-catalyzed aerobic oxidative reaction to synthesize disubstituted isoxazoles from homopropargylic alcohol, t-BuONO, and H2O is developed. The method provides mild conditions to afford a variety of useful substituted heterocycles in an efficient and regioselective manner. The mechanism has been studied and proposed, which indicates that the transformation can be realized through construction of a C═N bond and C═O bond, C-H oxidation, and then cyclization. Moreover, this method can be enlarged to gram scale.


Subject(s)
Isoxazoles/chemical synthesis , Catalysis , Cyclization , Hydrogen Bonding , Iron/chemistry , Isoxazoles/chemistry , Molecular Structure , Oxidation-Reduction
6.
Org Lett ; 16(21): 5616-9, 2014 Nov 07.
Article in English | MEDLINE | ID: mdl-25317985

ABSTRACT

A silver-promoted oxidative cyclization of 1,6-enynes with disubstituted phosphine oxides is developed for the synthesis of fluorene derivatives. The reaction proceeds with high regioselectivity by constructing one C-P bond and two C-C bonds in one step. Moreover, reduction of the pentavalent phosphine enlarges the application scope of the product.


Subject(s)
Alkynes/chemistry , Fluorenes/chemical synthesis , Phosphines/chemistry , Silver/chemistry , Catalysis , Cyclization , Fluorenes/chemistry , Molecular Structure , Oxidation-Reduction , Stereoisomerism
7.
Chem Commun (Camb) ; 50(69): 9936-8, 2014 Sep 07.
Article in English | MEDLINE | ID: mdl-25033417

ABSTRACT

A direct nitration of aromatic sulfonamides using sodium nitrite as the nitrating agent has been developed. The reaction shows typically mono-substitution selectivity and can be enlarged to the gram scale with good yield.

8.
Angew Chem Int Ed Engl ; 53(29): 7629-33, 2014 Jul 14.
Article in English | MEDLINE | ID: mdl-24938432

ABSTRACT

A novel copper-catalyzed one-pot functionalization of homopropargylic alcohols that involves trifluoromethylation, aryl migration, and formation of a carbonyl moiety has been developed. This reaction constitutes the first direct conversion of homopropargylic alcohols into CF3-containing 3-butenal or 3-buten-1-one derivatives in a regioselective manner. Mechanistic studies indicate that the 1,4-aryl migration proceeds through a radical pathway.


Subject(s)
Alcohols/chemistry , Chlorofluorocarbons, Methane/chemistry , Copper/chemistry , Catalysis , Methylation
9.
Chemistry ; 19(43): 14420-4, 2013 Oct 18.
Article in English | MEDLINE | ID: mdl-24114879

ABSTRACT

Regioselective trifluoromethylation-cyclization: A method for copper-catalyzed trifluoromethylation-cyclization of simple enynes using the CC triple bond as a nucleophile is reported for the first time. The reaction proceeds efficiently in a highly regioselective manner to give various 5- or 6-exo-dig carbocycles and heterocycles in moderate to high yields.


Subject(s)
Alkynes/chemistry , Fluorine/chemistry , Heterocyclic Compounds/chemistry , Carbon/chemistry , Catalysis , Copper/chemistry , Cyclization , Heterocyclic Compounds/chemical synthesis , Methylation , Stereoisomerism
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