Synthesis of Chlorinated Bicyclic C-Fused Tetrahydrofuro[3,2-c]azetidin-2-ones

Al/N-based active Lewis pairs: isocyanate insertion products as efficient nucleophiles employed for the facile generation of highly functional molecules

The previously reported active Lewis pair (ALP) i Bu2Al–N(2-Ad)NC5H10 (1) (2-Ad = 2-adamantyl) is readily accessible by hydroalumination of the hydrazone H10C5N–N=(2-C10H14) with H–Al i Bu2. Treatment of 1 with two equivalents of isocyanates R-N=C=O yields six-membered AlC2N2O heterocycles 2 (2a, R = Ph; 2b, R = p-Tol) by dual insertion into the Al–N bonds. 2a reacts as a nucleophile with carboxylic acid chlorides R-C(O)–Cl [R = CH2 t Bu, p-Tol, H2CCH(Me)C6H4(4-CH2CHMe2) (Ibu-profen acid chloride), 0.5 (1,4-C6H4)] to afford by elimination of i Bu2AlCl and hydrolysis new triuret derivatives R-C(O)[N(Ph)C(O)]2–N(2-Ad)NC5H10 (3a to 3d) as colourless, sparingly soluble solids in moderate (3c) to high (3b) yields. The analogous reaction of 2a with (p-Tol)–C(Cl)=N(p-Tol) leads to the imidoyl derivative (p-Tol)N=C(p-Tol)[N(Ph)C(O)]2–N(2-Ad)NC5H10 (4a), which showed a fast exchange of phenyl and tolyl groups to yield a mixture of isomers. The analogous reaction of 2b affords the corresponding compound 4b for which a single isomer is isolated despite the scrambling of substituents.

Changing stereoselectivity and regioselectivity in copper(i)-catalyzed 5-exo cyclization by chelation and rigidity in aminoalkyl radicals: synthesis towards diverse bioactive N-heterocycles

Chelation, rigidity and carbon-radical positions in aminoalkyl precursors disturb the usual 2,4-trans diastereoselectivity and 5-exo mode in Cu(i)-catalyzed ATRC.

Cascade Annulation of 2-Alkynylthioanisoles with Unsaturated α-Bromocarbonyls Leading to Thio-Benzobicyclic Skeletons

A protocol of Cu-catalyzed annulation of phenylethynylsulfanes with unsaturated α-bromocarbonyls for the construction of thio-benzobicyclic skeletons is described. In this single reaction, three new bonds and two new rings can be established, highlighting the step-economics and high efficiency of this protocol.

Copper(I)/Ligand-Catalyzed 5-endo Radical Cyclization-Aromatization of 2,2,2-Trichloroethyl Vinyl Ethers: Synthesis of 2,3-Difunctionalized 4-Chlorofurans

Copper(I)/ligand-catalyzed one pot synthesis of highly substituted 2,3-difunctionalized-4-chlorofurans has been reported. The reaction proceeds via a Cu(I)-catalyzed regioselective 5-endo-trig radical cyclization of 2,2,2-trichloroethyl vinyl ethers followed by the base-promoted dehydrochlorination. The success of the kinetically disfavored 5-endo cyclization was attributed to the formation of captodatively stabilized radical intermediate in the cyclization step and relatively high reaction temperature. Synthetic application of this protocol was also demonstrated in the preparation of alkyl and aryl substituted 4-chlorofuranonapthoquinones.

Recent developments in the synthesis of condensed β-lactams

β-Lactams are important heterocycles with diverse pharmacological profiles and have emerged as useful organic synthons.