A novel, tandem construction of C-N and C-C bonds: facile and one-pot transformation of the Baylis-Hillman adducts into 2-benzazepines

A novel reaction involving tandem construction of C-N and C-C bonds via the simultaneous Ritter and Houben-Hoesch reactions on Baylis-Hillman adducts leading to a convenient, one-pot synthesis of 2-benzazepine derivatives is described. A facile stereoselective transformation of the Baylis-Hillman adducts into (E)- and (Z)-allyl amides is also presented.     

Synthesis of 3,4-disubstituted 2(1H)-quinolinones via intramolecular Friedel-Crafts reaction of N-arylamides of Baylis-Hillman adducts

3,4-Disubstituted 2(1H)-quinolinones were synthesized starting from the Baylis-Hillman adducts via the following sequential processes: (i) hydrolysis of the Baylis-Hillman adduct to acid, (ii) EDC coupling with anilines, (iii) H₂SO₄-assisted intramolecular Friedel-Crafts cyclization, and the final (iv) DBU-mediated isomerization.     

Simple, facile and one-pot conversion of the Baylis-Hillman acetates into 3,5,6-trisubstituted-2-pyridones

A facile route for the synthesis of novel 3,5,6-trisubstituted-2-pyridones from the acetylated Baylis-Hillman esters with β-enamino esters or β-enamino nitriles in one pot with good yields is described.     

A facile one-pot stereoselective synthesis of trisubstituted (E)-2-methylalk-2-enoic acids from unactivated Baylis-Hillman adducts and a simple access to some important insect pheromones

An efficient one-pot stereoselective synthesis of trisubstituted (E)-2-methylalk-2-enoic acids has been accomplished by treatment of unactivated Baylis-Hillman adducts, 3-hydroxy-2-methylenealkanoates, with Al-NiCl₂·6H₂O in methanol at room temperature followed by hydrolysis. The method has been applied to the synthesis of three important insect pheromones, (4S,2E)-2,4-dimethyl-2-hexenoic acid, (+)-(S)-manicone and (+)-(S)-normanicone.     

Direct one-pot introduction of 2-methylpyridines to Baylis-Hillman adducts via base-mediated 3-aza-Cope rearrangement

An efficient and regioselective introduction method of 2-methylpyridines to the secondary position of Baylis-Hillman adducts has been developed. A base treatment of 2-methylpyridinium salt of Baylis-Hillman bromide generated N-allylenamine intermediate which underwent a facile 3-aza-Cope rearrangement under mild conditions to produce the product.     

Applications of Baylis-Hillman acetates: one-pot, facile and convenient synthesis of substituted γ-lactams

A simple, convenient and one-pot transformation of the acetates of Baylis-Hillman adducts into substituted γ-lactams, that is, (E)-5-alkyl-3-arylidenepyrrolidin-2-ones via treatment with nitroalkanes in the presence of a base, followed by reductive cyclization, using Fe/AcOH, is described.     

Applications of Baylis-Hillman adducts: a simple, convenient, and one-pot synthesis of 3-benzoylquinolines

A simple and convenient synthesis of 3-(2-hydroxybenzoyl)quinoline derivatives via the treatment of 3-[hydroxy(2-nitroaryl)methyl]-4H-chromen-4-ones, derived from chromones and various 2-nitrobenzaldehydes, with Fe/AcOH, in a one-pot operation, is described.     

TiCl4 catalyzed tandem construction of C-C and C-O bonds: a simple and one-pot atom-economical stereoselective synthesis of spiro-oxindoles

An atom-economical stereoselective synthesis of [{1-acetyl-5-methyl-6,8-dioxabicyclo(3.2.1)octane}-7-spiro-3'-(indolin-2'-one)] derivatives, containing both the oxindole and 6,8-dioxabicyclo(3.2.1)octane moieties via TiCl(4) catalyzed coupling of 2-acetyl-6-methyl-2,3-dihydro-4H-pyran with isatin derivatives is described.     

Facile synthesis of 2H-indazole derivatives starting from the Baylis-Hillman adducts of 2-cyclohexen-1-one

Facile synthetic method of 2H-indazole derivatives was developed involving DDQ oxidation of pyrazoles, which were prepared starting from the Baylis-Hillman adducts of 2-cyclohexen-1-one.     

Chemical transformation of Baylis-Hillman adducts: the reaction of methyl 3-arylamino-2-methylene-3-phenylpropanoates in polyphosphoric acid

We synthesized some interesting compounds including 3-benzylidene-3,4-dihydro-1H-quinolin-2-one, 3-benzylquinolin-2-ol, 4-amino-2-benzylideneindan-1-one, and 1-amino-9a,10-dihydro-4bH-indeno[1,2-a]inden-9-one skeletons starting from Baylis-Hillman adducts.     

SmI2-mediated elimination reaction of Baylis-Hillman adducts controlled by temperature: a facile synthesis of trisubstituted alkenes and 1,5-hexadiene derivatives with E-stereoselectivity

Promoted by samarium diiodide, the Baylis-Hillman adducts undergo hydroxyl elimination to form trisubstituted alkenes with total (E)-stereoselectivity in good to excellent yields. The flexibility of this method also opens a new route to synthesize a class of 1,5-hexadiene derivatives by temperature tuning.     

Simple and one-pot synthesis of tri and tetracyclic frameworks containing [1,8]naphthyridin-2-one moiety from the Baylis-Hillman adducts

A facile synthesis of tri and tetracyclic frameworks containing [1,8]naphthyridin-2-one skeleton from the Baylis-Hillman alcohols via the Johnson-Claisen rearrangement, followed by the treatment with Fe/AcOH in simple one-pot multi-step process is described.     

Remarkable rate acceleration of water-promoted nucleophilic substitution of Baylis-Hillman acetate: a facile and highly efficient synthesis of N-substituted imidazole

Without additional reagents, the Baylis-Hillman acetates 2 underwent nucleophilic substitution reaction with imidazole readily in aqueous THF solution to afford the corresponding N-substituted imidazole derivatives 3 in good to excellent yields. Moreover, the reaction between the in situ generated DABCO salt of Baylis-Hillman acetates 4 and imidazole occurs in aqueous THF providing the S_N2 type products 5. The simpler operational procedure, better stereoselectivity and higher efficiency over conventional method make the present protocol practical for the preparation of imidazole derivatives.     

Regioselective construction of polysubstituted phenols from Baylis-Hillman adducts via formal [4+2] annulation strategy

Polysubstituted phenol derivatives were synthesized regioselectively starting from the Baylis-Hillman adducts via the formal [4+2] annulation protocol as the key step.     

A highly efficient stereoselective synthesis of (Z)- and (E)-allyl iodides from Baylis-Hillman adducts

A highly efficient synthesis of (Z)- and (E)-allyl iodides has been accomplished by treatment of Baylis-Hillman adducts with iodine and triphenylphosphine in methylene chloride at room temperature. The method is associated with mild reaction conditions, high yields and excellent stereoselectivity.     

Pd-mediated synthesis of novel pentacyclic benzoazepino[2,1-a]isoindoles from enamides of Baylis-Hillman adducts

Novel pentacyclic benzoazepino[2,1-a]isoindole derivatives were synthesized by palladium-mediated consecutive cyclization from enamides of Baylis-Hillman adducts.     

Synthesis of 2-amino-2,3-dihydrobenzofurans and fully substituted furans from modified Baylis-Hillman adducts

Syntheses of 2-amino-2,3-dihydrobenzofuran derivatives 3a-g and fully substituted furans 5a-f were achieved starting from the Baylis-Hillman adducts. We prepared 2-amino-2,3-dihydrobenzofurans from the Baylis-Hillman adducts of methyl and ethyl acrylates and fully substituted furans from the Baylis-Hillman adducts of alkyl vinyl ketones.     

A facile tandem protocol for the regioselective synthesis of novel thienobenzothiazepines

A series of new 3-benzyl-1,10-diaryl-4H,10H-thieno[3,4-c][1,5]benzothiazepines has been synthesised regioselectively from the reaction of 5-aryl-2,4-bis(arylmethylidene)dihydro-3-thiophenones with o-aminothiophenol in the presence of acetic acid. This transformation presumably occurs via a tandem Michael addition-condensation-isomerisation sequence.     

Regio- and stereoselective reactions between cyclic Baylis-Hillman type adducts and N-nucleophiles and P-nucleophile

New important organic compounds multifunctionalized cyclic 6-membered and 7-membered allylic amines, azide and phosphonates have been obtained via regio- and diastereoselective reactions of cyclic Baylis-Hillman type adducts 1 with N-nucleophiles and P-nucleophile. We have found that the reactions proceed by S_N2 or S_N2′ processes exclusively, or by both processes simultaneously. The S_N2′ process occurs with anti stereochemistry.     

Synthesis and characterization of chiral enantiopure bis-chromanones: a Baylis-Hillman approach

Enantiopure bis-chromanones were prepared from (S)-Binol and bromo esters via a Baylis-Hillman approach. Chiroptical studies indicate that the two-naphthyl units of the chromanone system are non-coplanar.