Access to N-Fused Quinazolinones by Radical-Promoted Cascade Annulations of Alkenyl N-Cyanamides with Aromatic Aldehydes.

A cascade radical cyclization of alkenyl N-cyanamides with aromatic aldehydes has been achieved for an expeditious synthesis of keto-methylated dihydropyrrolo-quinazolinones. Benzoyl radicals, generated from aryl aldehydes in the presence of di-tert-butyl peroxide (DTBP), promoted the domino annulations leading to distinctive functionalized quinazolinones in good yields. In addition, the robustness of the present protocol is validated by employing heterocyclic and natural product-based aldehydes.

Access to CF3-benzofulvenes via palladium-catalyzed cascade arylation/Trost-Oppolzer cyclization/double-bond isomerization.

Herein, we demonstrated a Pd-catalyzed cascade reaction that involves arylation, Trost-Oppolzer type Alder ene reaction, and double bond isomerization using the 4-(2-alkynylphenyl)-allylcarbonates and aryl boronic acids. This cascade process delivers a wide array of distinctive functionalized CF3-benzofulvenes in good yields with high stereoselectivity (E). A single palladium catalyst orchestrates the two individual reactions in a single operation. Trost-Oppolzer type Alder ene reaction is the key in this transformation, also called a rare acid-free iso-Nazarov type cyclization.

Aminative annulation of cyano-enynyl esters leading to functionalized cyclopentenones.

A base-mediated unexpected aminative carbo-cyclization of cyano-enynyl esters, generated from Morita-Baylis-Hillman (MBH) acetates of propiolaldehydes, with secondary-amines is described. This metal-free reaction allows the synthesis of a unique cyclopentenone bearing an exocyclic double bond (cyano-olefin) with high E-selectivity in good yields. The synthetic potential of this annulation was further exemplified by the derivatization of bioactive molecules, a scale-up synthesis and synthetic transformations of the obtained cyclopentenone.

Domino Aza-Annulations of Enynyl-/(Alkynyl)aryl-acetonitriles to Access Nitrogen-Enriched Heterocycles.

Unprecedented domino aza-annulations of (E)-2-en-4-ynyl-acetonitriles (generated from the Morita-Baylis-Hillman acetates of propiolaldehydes for the first time) with sodium azide under metal- and oxidant-free conditions for the assembly of triazolo-pyridines are accomplished. The developed strategy offers broad substrate scope, extending to (2-alkynyl)aryl and indolyl-acetonitriles to provide the corresponding triazolo-fused isoquinolines and ß-carbolines, respectively, in good yields. Additionally, the synthetic utility of the products is demonstrated via denitrogenative coupling of fused triazoles with different nucleophiles.

3-Trifluoroacetyl-quinolin-2(1H)-ones as Carbonyl and Acid Surrogates in the Passerini-/Ugi-Type Reaction.

Herein, we report tailored 3-trifluoroacetyl-quinolin-2(1H)-ones (1) as carbonyl and acid surrogates in Passerini- and Ugi-type reactions for the synthesis of α-trifluoromethyl-α-hydroxy carboxamides (4) and α-trifluoromethyl α-amino acids (6) in high yields, respectively. The reaction proceeds under mild reaction conditions via an exocyclic carboximidate intermediate (3). The amide group in compound 1 acts as an acid component as well as a reversible oxygen nucleophile to facilitate the reaction.

Palladium-catalyzed ortho-vinylation of ß-naphthols with α-trifluoromethyl allyl carbonates: one-pot access to naphtho[2,1-b]furans.

Highly regio- and stereoselective palladium-catalyzed ortho-vinylation of ß-naphthols (2) has been reported using easily accessible CF3-allyl carbonates (1). The regioselective nucleophilic γ-attack of the CF3-π-allyl-Pd-intermediate is the key to furnish (Z)-CF3-vinylnaphthols (3) in good yields. Furthermore, we achieved a one-pot synthesis of CF3-naphtho[2,1-b]furans (4) through an uninterrupted ortho-vinylation/oxidative radical cyclization reaction sequence.

Facile access to [1,2]-oxazine derivatives via annulations of aminoxy-tethered 1,7-enynes.

An efficient approach for the highly diastereoselective construction of functionalized cyclopenta[d][1,2]oxazines via sequential oxyamination and Pauson-Khand reaction of readily accessible propargylic alcohols has been developed. Furthermore, the ring closing metathesis of these N-O linked 1,7-enynes afforded vinylated-[1,2]oxazines in good yields. The reduction of the N-O bond of the obtained cyclopenta[d][1,2]oxazine is accomplished to access cyclopentenone-based amino alcohols.

Silver-catalyzed acylative annulation of N-propargylated indoles with α-keto acids: access to acylated pyrrolo[1,2-a]indoles.

This study describes the first carbon centered radical cyclization of N-propargyl indoles involving decarboxylation of α-keto acids in the presence of an Ag-catalyst. The present cascade carbon-carbon bond formation reactions provide C-acylated pyrrolo[1,2-a]indoles in good yields (25 examples). The amount of oxidant has a profound effect on the reaction to convert either the di-acylated products using 8 equiv. of K2S2O8 or mono-acylated products using 2 equiv. of K2S2O8. N-Propargyl pyrroles are also found to be suitable for delivering the corresponding 3H-pyrrolizines.

Synthesis of Both Enantiomers of Nine-Membered CF3 -Substituted Heterocycles Using a Single Chiral Ligand: Palladium-Catalyzed Decarboxylative Ring Expansion with Kinetic Resolution.

The two enantiomers of trifluoromethyl-benzo[c][1,5]oxazonines, (R)-4 and (S)-4, can be selectively accessed with high enantiopurity by the Pd-catalyzed ring-expansion reaction of trifluoromethyl-benzo[d][1,3]oxazinones (1) with vinyl ethylene carbonates (3) using one antipode of a chiral ligand. Initially, the reaction proceeds by a double decarboxylative ring-expansion with kinetic resolution of 1 in the presence of a Pd-catalyst/chiral ligand to provide (R)-4 with high enantiopurity. At the same time, the nonreactive antipode of 1, (S)-1, which was recovered with an impeccable s factor of up to 713 and an ideal chemical yield, was transferred into the antipode of the products, (S)-4, with high enantiopurity by a second run of the Pd-catalyzed double decarboxylation reaction, but this time without any chiral auxiliary. Thus, both antipodes of the chiral trifluoromethyl heterocycles 4 can be obtained in excellent enantiopurity using only a single antipode of the chiral catalyst.

Diastereoselective synthesis of CF3-dihydrobenzofurans by [4+1] annulation of in situ-generated CF3-o-quinone methides and sulfur ylides.

An efficient and highly diastereoselective synthesis of CF3-dihydrobenzofurans by the reaction of in situ-generated CF3-oQMs in the presence of a base with sulphur ylides is put forward. The generality of the present developed method was well studied with diverse substrates to access the corresponding products in excellent yields. The highly reactive CF3-oQM has been utilized first time for the annulation reaction.

Gas/Liquid-Phase Micro-Flow Trifluoromethylation using Fluoroform: Trifluoromethylation of Aldehydes, Ketones, Chalcones, and N-Sulfinylimines.

Invited for this month's cover picture is the group of Norio Shibata at the Nagoya Institute of Technology (Japan). The cover picture shows an image related to the perpetual motion machine of the second kind in the eighteenth century, and "alchemy". Our biggest challenge on the path to the results presented in this paper was the creation of alchemy using fluorine chemistry. Read the full text of their Communication at 10.1002/open.201800286.

Gas/Liquid-Phase Micro-Flow Trifluoromethylation using Fluoroform: Trifluoromethylation of Aldehydes, Ketones, Chalcones, and N-Sulfinylimines.

A micro-flow nucleophilic trifluoromethylation of carbonyl compounds using gaseous fluoroform was developed. This method also allows the first micro-flow transformation of N-sulfinylimines into trifluoromethyl amines with excellent diastereoselectivity. To demonstrate the synthetic utility of this micro-flow synthesis, the formal micro-flow synthesis of Efavirenz is described.

Pd-Catalyzed Decarboxylative Cyclization of Trifluoromethyl Vinyl Benzoxazinanones with Sulfur Ylides: Access to Trifluoromethyl Dihydroquinolines.

An unprecedented Pd-catalyzed decarboxylative cyclization of 4-trifluoromethyl-4-vinyl benzoxazinanones (4) with sulfur ylides (2) is reported. While the reactions of 4-vinyl/4-CF3 benzoxazinanones (1a/1c) with 2 furnished the 3-vinyl/3-CF3 indolines (3a/3c), via an attack on the C1 carbon of the π-allyl/benzyl zwitterionic intermediates, 4 was converted into 4-trifluoromethyl-dihydroquinolines (5) in good yields via an attack on the C3 carbon of the π-allyl intermediate. The corresponding methyl-substituted analogues afford different products via an attack on the C2 carbon.

Stille cross-coupling of secondary and tertiary α-(trifluoromethyl)-benzyl chlorides with allylstannanes.

A Stille cross-coupling reaction was developed that delivers for the first time trifluoromethyl-substituted homoallyl compounds from α-(trifluoromethyl)benzyl chlorides and allylstannanes. This reaction proceeds even with low catalyst loadings (1 mol%) via a rare CF3-Pd-π-benzyl intermediate.

Stereodivergent trifluoromethylation of N-sulfinylimines by fluoroform with either organic-superbase or organometallic-base.

Here we have successfully demonstrated the first stereodivergent direct nucleophilic trifluoromethylation of N-sulfinylimines using the potent greenhouse gas "HFC-23, fluoroform" with an organic-superbase or an organometallic-base in high yields and selectivity.

Highly Diastereoselective Synthesis of Trifluoromethyl Indolines by Interceptive Benzylic Decarboxylative Cycloaddition of Nonvinyl, Trifluoromethyl Benzoxazinanones with Sulfur Ylides under Palladium Catalysis.

A highly diastereoselective synthesis of trifluoromethyl-substituted indolines under palladium catalysis is disclosed. The reaction proceeds by interceptive decarboxylative benzylic cycloaddition (IDBC) of nonvinyl, trifluoromethyl benzoxazinanones with sulfur ylides. The palladium-π-benzyl zwitterionic intermediates are suggested for this transformation, and this would be the first example of an IDBC reaction.

Synthesis of novel 1,2-benzothiazine 1,1-dioxide-3-ethanone oxime N-aryl acetamide ether derivatives as potent anti-inflammatory agents and inhibitors of monocyte-to-macrophage transformation.

A series of novel 1,2-benzothiazine 1,1-dioxide-3-ethanone oxime N-aryl acetamide ether derivatives 7a-h and 9a-h were synthesized starting from sodium salt of saccharin 1 in series of steps. Final compounds 7a-h and 9a-h were evaluated for the anti-inflammatory activity and their ability to inhibit monocyte-to-macrophage transformation. Compounds 7e, 9b, 9e and 9h showed impressive anti-inflammatory activities (TNF-α, IL-8 and MCP-1) at micro molar concentration which was found to be better than positive control i.e., piroxicam. Compound 9e marginally and compound 9h significantly inhibited PMA-induced MMP-9 gelatinase activity. Also compounds 9e and 9h greatly inhibited the PMA-induced monocyte-to-macrophage transformation, a pre-requisite step in the formation of atheroma.