A practical and environmentally friendly strategy for generating alkoxycarbonyl radicals from readily available carbazates under metal‐free conditions has been developed. In the presence of tetrabutylammonium iodide and tert‐butyl hydroperoxide, 2‐isocyanobiphenyls smoothly underwent radical alkoxycarbonylation with carbazates to afford phenanthridine‐6‐carboxylates.
A concise synthesis of 1‐naphthols via cyclization of o‐iodoacetophenones and methyl ketones has been realized under very mild conditions. The cyclization process is initiated by a rare copper‐catalyzed arylation of simple methyl ketones with ortho‐iodoacetophenones.
A practical, nickel‐catalyzed Kumada‐type double cross‐coupling reaction of gem‐difluoroalkenes with 1,4‐ or 1,5‐di‐Grignard reagents was developed. The reaction proceeded efficiently at room temperature and a variety of cyclization products, arylmethylenecyclopentanes and arylmethylenecyclohexanes, were obtained in high to excellent yields, respectively.
A transition metal‐free direct arylation of 2‐substituted cyanoacetates with diaryliodonium salts was developed. With this approach, a wide range of α‐tolunitrile derivatives has been synthesized in good to excellent yields of 45–92%. Furthermore, the practicability of this approach is further manifested in the synthesis of a related bioactive agent of glutarimide.
A transition metal‐free and efficient method for the synthesis of 3‐alkynylpyrrole‐2‐carboxylates from diynones and glycine esters or 2‐aminoacetophenone hydrochloride has been developed. This transformation provides a large range of substituted pyrroles in good to excellent yields with the elimination of water as the only by‐product. The detailed mechanistic studies elucidated that this transformation involves a Michael addition/intramolecular cyclodehydration process.
A sequential benzoin/Michael/acetalization tandem reaction catalyzed by NHC and amine together has been developed to assemble aromatic aldehydes and enals into chiral tetrahydrofuran derivatives bearing multiple functional groups and stereogenic centers with high stereoselectivity of up to 95:5 dr and 96% ee. The high yield and stereocontrol of this process may be due to both acid‐promoted symmetrization of racemic acyloins and iminium ion activation of enals.
A palladium‐catalyzed trans‐hydroalkynylation of N‐sulfonyl ynamides has been achieved for the first time, providing α‐alkynylation adducts in high yields with excellent regio‐ and stereoselectivity. The resulting enyne products can serve as the useful precursors for the elaboration of naphthalene derivatives via a platinum‐catalyzed cycloisomerization reaction.
A divergent approach to generate either 1‐hydroxymethylindenes (which could then be converted to benzofulvenes through a dehydration reaction) or naphthalenes by the rearrangement of cycloprop[2,3]inden‐1‐ols is reported. The effect of the cyclopropyl ring substitution pattern on ring‐opening/expansion rearrangements of the substrates was systemically studied.
A facile one‐pot, catalyst‐free reaction has been developed for the synthesis of 2,3,6,7‐tetrahydro‐1H‐pyrrolo[3,2‐c]pyridin‐4(5H)‐ones from readily available 1‐acryloyl‐1‐N‐arylcarbamylcyclopropanes and amines using a domino ring‐opening/cyclization/aza‐addition sequence.
We disclose herein an efficient enantioselective conjugate addition reaction between coumarin‐3‐carboxylic acids and malonic acid half thioesters (MAHTs). The reaction was catalyzed by N‐heteroarenesulfonyl Cinchona alkaloid amides to afford double‐decarboxylative conjugate addition products in good yield with high enantioselectivity. The reaction of various coumarin‐3‐carboxylic acids with MAHTs gave products in high yield with high enantioselectivity.
A novel asymmetric [4+2] annulation of vinyl ketones with oxindole‐derived α,β‐unsaturated imines has been developed in the presence of a multifunctional thiourea‐phosphine catalyst derived from a natural amino acid, providing the first phosphine‐catalyzed enantioselective synthesis of 2′,3′‐dihydro‐1′H‐spiro[indoline‐3,4′‐pyridin]‐2‐ones in good yields with excellent stereoselectivities under mild conditions.
This report presents a new, one‐pot, facile, selective and green method for methoxycarbonylation of alcohols and synthesis of five‐ and six‐membered cyclic carbonates from corresponding alcohols with dimethyl carbonate (DMC) in the presence of molecular sieves without any additional solvent and catalyst. Syntheses of bifunctional structures comprising a six‐membered cyclic carbonate with allyl ether and methacrylate groups, respectively, for different polymerization modes, were also achieved and showed reproducibility on up‐scaling the processes.
Organocatalyzed highly stereoselective 1,4‐thia‐Michael addition of mercaptans to linear 2,4‐dienones and 2‐en‐4‐ynones was developed using Cinchona alkaloid‐based squaramides. Application of only 0.5–1 mol % loading afforded products in up to 98:2 e.r. and above 99:1 after a single recrystallization. The adducts of allyl mercaptan can be conveniently further transformed to new chiral 2‐substituted 2,5‐dihydrothiophenes by ring‐closing metathesis.
A new copper‐mediated synthesis of α‐sulfonylethanone oximes from styrenes, sodium arylsulfinates and tert‐butyl nitrite (t‐BuONO; TBN) is presented. This intermolecular three‐component method enables the one‐step formation of C N and C S bonds under mild conditions, and represents a new, straightforward approach to α‐sulfonylethanone oximes.
