Diversity-Oriented Approaches to Unusual α-Amino Acids and Peptides: Step Economy, Atom Economy, Redox Economy, and Beyond

Total synthesis of an anticancer norsesquiterpene alkaloid isolated from the fungus Flammulina velutipes

The first total synthesis of a norsesquiterpene alkaloid (R)-8-hydroxy-4,7,7-trimethyl-7,8-dihydrocyclopenta[e]isoindole-1,3(2H,6H)-dione, isolated from the mushroom-forming fungus Flammulina velutipes, in both racemic and enantiomeric pure forms, is reported. The (-)-enantiomer of the natural product has been synthesized from the D-(-)-pantolactone chiral pool. The synthesis features a one-pot, three-step reaction sequence comprising an enyne RCM/Diels-Alder/aromatization to construct the desired indane skeleton present in the natural product. Our synthesis further confirms the assigned structure and absolute configuration of the natural product.

Diversified syntheses of multifunctionalized thiazole derivatives via regioselective and programmed C-H activation

The sequential construction of diversified multifunctionalized thiazole derivatives through Pd-catalyzed regioselective C-H alkenylation has been accomplished. This versatile approach provides the diversified thiazole derivatives featuring orthogonal substitution patterns at the C-2, C-4 and C-5 positions from mono-substituted (2- or 4-substituted) thiazole derivatives or even more challenging simple thiazole.

CuO nanostructures of variable shapes as an efficient catalyst for [3 + 2] cycloaddition of azides with terminal alkyne

CuO nanowires exhibited highest catalytic efficiency for the cycloaddition reaction between azide and terminal alkyne, featuring short reaction time, soft reaction conditions and complete regioselectivity.

Intramolecular functional group differentiation as a strategy for the synthesis of bridged bicyclic β-amino acids

Differentiation of identical electrophilic functional groups (carboxylates) by a strategically placed internal nucleophile (an amino group) in cyclic precursors was used as a key general approach to functionalized azabicyclic scaffolds.

A diversity-oriented approach to indolocarbazoles via Fischer indolization and olefin metathesis: total synthesis of tjipanazole D and I

New synthetic strategies to indolocarbazoles have been reported via two-fold Fischer indolization under green conditions using l-(+)-tartaric acid and N,N-dimethyl urea.

Unprecedented one-pot chemocontrolled entry to thioxoimidazolidinones and aminoimidazolones: synthesis of kinase inhibitor leucettamine B

A novel and highly chemoselective protocol for the construction of thioxoimidazolidinone and aminoimidazolone frameworks was explored, and the influence of the reaction conditions on product formation was studied to establish two distinct approaches for their selective formation. In this one-pot reaction, ambient temperature generally resulted in the formation of thioxoimidazolidinones, whereas microwave irradiation provided aminoimidazolones exclusively. An attempt to elucidate the observed chemoselectivity is described, and the products were confirmed by X-ray studies. One-pot synthesis toward Leucettamine B, a marine alkaloid, was achieved on the basis of this protocol.

One-pot quadruple/triple reaction sequence: a useful tool for the synthesis of natural products

Multiple reactions in one pot has always been a useful technique for synthetic organic chemists, as it can minimizes solvent usage, time and the number of purification steps when compared to individual multi-step syntheses. In line with this, here in this perspective we discuss a one-pot quadruple/triple reaction sequence comprising an enyne ring-closing metathesis/cross-metathesis/Diels-Alder/aromatization for the synthesis of natural products setting.

Synthesis of new unnatural N(α)-Fmoc pyrimidin-4-one amino acids: use of the p-benzyloxybenzyloxy group as a pyrimidinone masking group

The p-benzyloxybenzyloxy group is used to mask the oxo function of the 4(3H)-pyrimidinone ring in the synthesis of new unnatural amino acids. The synthetic approach is based on an aromatic nucleophilic substitution reaction between 4-[4-(benzyloxy)benzyloxy]-2-(benzylsulfonyl)pyrimidine and the nucleophilic side chain of several N(α)-Boc amino esters, as the key step, followed by a series of standard protecting group transformations. p-Benzyloxybenzyloxy is efficiently removed under mild acid conditions to recover the 4(3H)-pyrimidinone system.

Zinc mediated allylations of chlorosilanes promoted by ultrasound: Synthesis of novel constrained sila amino acids

A simple, fast and efficient method for allylation and propargylation of chlorosilanes through zinc mediation and ultrasound promotion is reported. As a direct application of the resulting bis-allylsilanes, three novel, constrained sila amino acids are prepared for the first time.