Herein we describe a scalable approach to the decalin moiety of maklamicin. Key to the synthesis is an intramolecular Diels-Alder (IMDA) reaction that proceeds via an endo-axial transition state to generate the desired stereochemistry. We explored the diastereoselectivity of the IMDA reaction as a function of both chiral catalysis and acyclic precursor stereochemistry.

[Structure: see text] Thermal treatment of 1,6-fullerenynes bearing an alkyl group on the terminal carbon of the alkyne moiety leads quantitatively to new allenes through a reaction mechanism involving an intramolecular ene process. This reaction outcome is in contrast to that recently found for free terminal alkynes which form cyclobutene derivatives through a [2+2] cyclization mechanism.

[reaction: see text]. Cyclic amines may be prepared via a sequence of deprotection followed by intramolecular reductive amination of t-Boc-protected amino ketones under asymmetric transfer hydrogenation conditions. In cases where the corresponding imine reaction proceeds with high enantioselectivity, this is reflected in the one-step process.

A highly enantioselective organocatalytic vinylogous aldol-cyclization cascade reaction of 3-alkylidene oxindoles to isatins has been achieved by using bifunctional organocatalysts. The unexpected intramolecular lactonization which follows the initial aldol reaction, leading to the cleavage of the oxindole ring and generation of enantioenriched spirooxindole dihydropyranones in good to excellen...

A Pd(0)-catalyzed intramolecular aryldifluoromethylation of activated alkenes under mild reaction conditions has been developed. This reaction provides a new method for construction of a variety of difluoromethylated oxindoles. Mechanistic investigations indicate that a difluoromethyl radical, which was triggered by Pd(0), initiated the cascade sequence through an addition to the alkene.

An enantioselective epoxidation of tryptophols followed by an intramolecular epoxide opening reaction was realized by chiral vanadium catalysts derived from C2 symmetric bis-hydroxamic acid (BHA) ligands. 3a-Hydroxyfuroindoline derivatives with up to 89% yield and 90% ee were obtained under mild reaction conditions.

The key steps in the synthesis of clavulactone are formation of an enantiopure cyclopentane precursor by epoxide rearrangement and intramolecular carbonyl-ene reaction, construction of the 3,4-dihydro-2H-pyran ring by intermolecular hetero-Diels-Alder reaction, closure of the eleven-membered ring, and finally generation of the lactone functionality by chemoselective allylic C(sp(3))-H oxidation.

An intramolecular cyclization of 2-(gem-dibromovinyl)phenols(thiophenols) to give 2-bromobenzofurans(thiophenes) in the presence of a trace amount of Cu (0.0064 mol%, 25 ppm) has been developed. The reaction provides the desired products in excellent yields under fluoride-free and mild reaction conditions and with a TON (turnover number) of up to 1.5 × 10(4).

The reaction of ethyl 2-ethynylphenylcarbamate derivative with alkenes in the presence of a palladium(II) catalyst, copper dichloride and tetrabutylammonium fluoride (TBAF) produced 2-substituted 3-ethenylindoles during refluxing. The intramolecular cyclization reaction of ethyl 2-ethynylphenylcarbamates, which have an ethenyl part in the ethynyl group, was also used to produce carbazole deriva...

This presentation discloses a one-pot synthesis of a series of spiropyrroloquinoline isoindolinone and spiropyrroloquinoline aza-isoindolinone scaffolds. The reaction proceeds by the combination of a Ugi four-component reaction (4CR) and two intramolecular cyclizations under metal-free conditions. The proof of the structures relies on analytical investigation and X-ray crystallography.