The palladium‐catalyzed oxidative Heck‐type allylation of β,β‐disubstituted enones, i.e., α‐oxoketene dithioacetals, was efficiently realized with allyl carbonates, providing a concise route to highly functionalized dienes. The present synthetic methodology utilizes the substrate activation strategy to activate the C H bond of β,β‐disubstituted enones by introduction of a 1,2‐dithiolane functionality to make the enone substrate highly polarized and thus increase its reactivity, demonstrating rare examples for transition metal‐catalyzed allylic substitution of ß,ß‐disubstituted enones through a Heck‐type allylation process.
Novel copper‐catalyzed three‐component reactions of phenylacetonitrile, sulfur and DMF (dimethyformamide) for the selective preparation of N,N‐dimethylthiobenzamide and N,N‐dimethyl‐2‐phenylethanethioamides in yields of up to 96% are described.
Efficient one‐step syntheses of α,β‐ and β,β‐dihaloenones were achieved by ruthenium(II)‐catalyzed reactions between cyclic or acyclic diazodicarbonyl compounds and oxalyl chloride or oxalyl bromide in moderate to good yields. This methodology offers several significant advantages, which include ease of handling, mild reaction conditions, one‐step reaction, and the use of an effective and non‐toxic catalyst. The synthesized compounds were further transformed into highly functionalized novel molecules bearing aromatic rings on the enone moiety using the Suzuki 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.
An enantioselective protonation by means of chiral scandium complex‐catalyzed aza‐Michael reaction was realized. A series of α‐aryl‐substituted vinyl ketones reacted with pyrazoles smoothly, affording the corresponding enantiomerically enriched pyrazole derivatives with excellent results (up to 99% yield, 94% ee). Water and hydrogen chloride were found to accelerate the protonation process.
A convenient gold‐catalyzed strategy for the synthesis of imidazo[1,2‐a]pyridine derivatives has been developed via gold carbene complexes. This transformation opens a new synthetic route to a variety of 3‐carbonyl‐substituted imidazo[1,2‐a]pyridines using air as oxidant affording the products in good yields.
A copper‐catalyzed cascade reaction involving trifluoromethylation of acrylamides coupled with ring closure and indole dearomatization is reported. This facile transformation was highly regioselective and proceeded under mild conditions, allowing efficient access to trifluoromethyl‐substituted spiro[indole‐3,3′‐pyrrolidine] derivatives, which are of increasing interest to the pharmaceutical industry.
An aluminium(III) chloride‐catalyzed three‐component reaction of aromatic aldehydes, nitroalkanes, and sodium azide has been developed; this reaction sequence can be applied to a broad substrate scope and affords the corresponding 4‐aryl‐NH‐1,2,3‐triazoles in good to excellent yields. The milder reaction conditions and easier operation make this AlCl3‐catalyzed protocol more advantageous for the synthesis of 4‐aryl‐NH‐1,2,3‐triazoles.
A facile and efficient one‐pot synthesis of isoxazol‐3(2H)‐ones has been developed starting from α‐acyl cinnamides and tosyliminophenyliodinane catalyzed by copper(II) acetate [Cu(OAc)2] under very mild conditions involving a tandem aza‐Michael addition and intramolecular cyclization sequence.
A cationic gold(I)‐catalyzed decarboxylative etherification of propargyl carbonates to selectively produce propargyl ethers is reported. In the reaction the gold(I) catalyst shows a distinct σ‐Lewis acidity rather than the commonly observed π‐Lewis acidity, and thus catalyzes the decarboxylation of a variety of propargyl carbonates to give the corresponding propargyl ethers with high selectivity. This reaction represents a rare example of the tunable reactivity of cationic gold(I) complexes between σ‐Lewis acidity and π‐Lewis acidity.
Copper chloride‐catalyzed aerobic oxidative annulation of N‐furfuryl‐β‐enaminones provides access to polysubstituted pyrroles and indoles. This protocol involves an unprecedented copper chloride‐catalyzed oxidative chlorination of furan and pyrrole rings with oxygen as the terminal oxidant.
A synthetic strategy has been developed for the synthesis of 2‐dialkylaminoquinolines from easily available quinoline N‐oxides, tertiary amines, diisopropyl H‐phosphonate and carbon tetrachloride (CCl4) in one pot under metal‐free conditions at room temperature.
Silver‐catalyzed three‐component, tandem reactions of 4‐alkynyl‐2‐oxo‐2H‐chromene‐3‐carbaldehydes, amines and various nucleophiles result in the formation of highly functionalized chromeno[3,4‐c]pyridin‐5‐ones in high yields. Gold‐catalyzed [4+2] cycloadditions of 4‐alkynyl‐2‐oxo‐2H‐chromene‐3‐carbaldehydes with alkynes or alkenes have also been achieved to afford benzo[c]chromen‐6‐ones efficiently.
A method for copper‐catalyzed aryltrifluoromethylation of N‐phenylcinnamamides is reported. This method provides a straightforward route to a variety of CF3‐containing 3,4‐dihydroquinolin‐2(1 H)‐ones with excellent regioselectivity and diastereoselectivity.
Various 3‐azabicyclo[3.1.1]heptane derivatives were synthesized from Morita–Baylis–Hillman adduct‐derived 1,3‐dienes bearing a 4,4‐diaryl moiety through a thermal intramolecular [2+2] cycloaddition approach. By using the same approach, bicyclo[3.1.1]heptane, 3‐azabicyclo[3.2.0]heptane, and 3‐oxabicyclo[3.1.1]heptane derivatives could also be synthesized. A structurally similar dimethylallyl derivative underwent an intramolecular ene reaction to afford the pyrrolidine derivative.
A general and efficient method for the synthesis of oxazolidin‐2‐ones and imidazolidin‐2‐ones directly from 1,3‐diols and 3‐amino alcohols has been developed using the same reagent combination of iodobenzene dichloride (PhICl2) and sodium azide (NaN3).
