Enantioselective Synthesis of α-Aryl-β-Aminocyclopropane Carboxylic Acid Derivatives via Rh(II)-Catalyzed Cyclopropanation of Vinylsulfonamides with α-Aryldiazoesters

The reaction of vinylsulfonamides with donor-acceptor carbenes derived from α-aryldiazoesters, catalyzed by the tert-butyl glycine-derived dirhodium complex Rh₂(S-4-Br-NTTL)₄, has been reported. This method provides a variety of α-aryl-β-aminocyclopropane carboxylic acid derivatives bearing one quaternary carbon stereogenic center vicinal to the amino-substituted carbon in high yields with excellent diastereo- and enantioselectivities. Vinylsulfonamides showed complementary advantages over the well-developed vinylamides or vinylcarbamates for this Rh(II)-catalyzed cyclopropanation strategy. Moreover, these conformationally restricted α-aryl-β-aminocyclopropyl carboxylic acid derivatives can be readily incorporated into dipeptides.

Diazocarbonyl derivatives of amino acids: unique chiral building blocks for the synthesis of biologically active compounds

This review deals with applications of chiral α-amino diazoketones, α-amino acid derivatives, in the synthesis of various biologically active compounds. General approaches to the synthesis of chiral α-amino diazoketones, including the Arndt – Eistert reaction, acylation of trimethylsilyldiazomethanes, etc., are discussed. Due to the presence of three functional groups, these building blocks can be used to produce a wide range of organic compounds with potential physiological activity, ranging from various heterocyclic compounds to peptidomimetics. Methods for the synthesis of β-amino acid-containing peptides and depsipeptides, amino acid derivatives and heterocyclic compounds with three- to seven-membered rings are considered.

The bibliography includes 226 references.

Ring-opening hydroarylation of monosubstituted cyclopropanes enabled by hexafluoroisopropanol

Ring-opening hydroarylation of cyclopropanes is typically limited to substrates bearing a donor-acceptor motif. Here, the transformation is achieved for monosubstituted cyclopropanes by using catalytic Brønsted acid in hexafluoroisopropanol (HFIP) solvent, constituting a rare example where such cyclopropanes engage in intermolecular C-C bond formation. Branched products are obtained when electron-rich arylcyclopropanes react with a broad scope of arene nucleophiles in accord with a simple SN1-type ring-opening mechanism. In contrast, linear products are obtained when cyclopropylketones react with electron-rich arene nucleophiles. In the latter case, mechanistic experiments and DFT-calculations support a homo-conjugate addition pathway.

Stereoselective synthesis of thiazino[4,3-a]indoles using the thia-Pictet-Spengler reaction of indoles bearing N-tethered thiols and vinylogous thiocarbonates

An inter- as well as intra-molecular thia-Pictet-Spengler cyclization of N-tethered thiols and vinylogous thiocarbonates is described for the stereoselective synthesis of N-fused thiazinoindole derivatives. The strategy is extended to one-pot, sequential Friedel-Crafts alkylation - Pictet-Spengler cyclization and the synthesis of thiazino-oxepino-indole.

Stereoselective synthesis of 2,3-disubstituted indoline, pyrrolidine and cyclic ether-fused 1,2-dihydroquinoline derivatives using alkyne iminium ion cyclization of vinylogous carbamates: switch of regioselectivity using an internal hydroxy group as a nucleophile

TMSOTf promoted alkyne iminium ion cyclization of vinylogous carbamates gives stereoselective access to indolines, pyrrolidines and dihydroquinolines.

Donor-acceptor substituted cyclopropane to butanolide and butenolide natural products: enantiospecific first total synthesis of (+)-hydroxyancepsenolide

An oxygen substituted donor-acceptor cyclopropane (DAC) is used as a common intermediate in the enantiospecific collective total synthesis of butanolide- and butenolide-based natural products like (+)-juruenolide C and D, (+)-blastmycinone, (+)-antimycinone, and (+)-ancepsenolide. Enantiospecific first total syntheses of (+)-hydroxyancepsenolide and its acetate are achieved confirming their absolute stereochemistry.

Stereoselective synthesis of C-fused pyranoindoles, pyranobenzofurans and pyranobenzothiophene scaffolds using oxa-Pictet–Spengler type reaction of vinylogous carbonates

C-fused pyranoheterocycles can be assembled in a highly diastereoselective manner using an intramolecular oxa-Pictet–Spengler type reaction of vinylogous carbonates.

Cyclization and annulation reactions of nitrogen-substituted cyclopropanes and cyclobutanes

This feature article covers recent progress in cyclization and annulation reactions of aminocyclopropanes and aminocyclobutanes to access nitrogen-rich building blocks.

Catalytic Friedel-Crafts reaction of aminocyclopropanes

A Lewis acid catalyzed Friedel-Crafts reaction between donor-acceptor aminocyclopropanes and indoles and other electron-rich aromatic compounds is reported. Indole alkylation at the C3 position was generally obtained for a broad range of functional groups and substitution patterns. In the case of C3-substituted indoles, C2 alkylation was observed. The reaction gives a rapid access to gamma amino acid derivatives present in numerous bioactive molecules.