Correction: Chigrinova, M., et al. Kinugasa reactions in water: from green chemistry to bioorthogonal labelling. Molecules 2015, 20, 6959-6969.

The authors wish to make the following correction to this paper [1]: The author name "Paul Pezacki" should be "John Paul Pezacki". [...].

Kinugasa reactions in water: from green chemistry to bioorthogonal labelling.

The Kinugasa reaction has become an efficient method for the direct synthesis of ß-lactams from substituted nitrones and copper(I) acetylides. In recent years, the reaction scope has been expanded to include the use of water as the solvent, and with micelle-promoted [3+2] cycloadditions followed by rearrangement furnishing high yields of ß-lactams. The high yields of stable products under aqueous conditions render the modified Kinugasa reaction amenable to metabolic labelling and bioorthogonal applications. Herein, the development of methods for use of the Kinugasa reaction in aqueous media is reviewed, with emphasis on its potential use as a bioorthogonal coupling strategy.

Strain-promoted cycloadditions involving nitrones and alkynes--rapid tunable reactions for bioorthogonal labeling.

The development and applications of strain-promoted alkyne-nitrone cycloaddition (SPANC) reactions have brought about new tools for rapid and specific functionalization of biomolecules in different settings. While a number of strain-promoted reactions have been successfully developed, SPANC reactions offer high reactivity with bimolecular rate constants of k2 that are as fast as 60M(-1)s(-1). SPANC reactions also offer stability of starting materials, particularly in the case of endocyclic nitrones, as well as stereoelectronic tunability of the nitrone moiety to optimize reactivity towards different alkyne reaction partners. Herein we discuss recent advances in the development of SPANC reactions and their applications in bioorthogonal labeling.

Synthesis of highly substituted cyclobutane fused-ring systems from N-vinyl beta-lactams through a one-pot domino process.

In this contribution, aminocyclobutanes, as well as eight-membered enamide rings, have been made from N-vinyl beta-lactams. The eight-membered products have been formed by a [3,3]-sigmatropic rearrangement, whereas the aminocyclobutanes have been derived from a domino [3,3]-rearrangement/6pi-electrocyclisation process. The aminocyclobutanes have been obtained in a highly diastereoselective fashion. The cyclobutane ring system tolerates fusion even if adjacent quaternary centres are present. Systems containing up to four fused rings are readily accessible. The reaction profile has been investigated by using Gaussian 03. This study suggests that two reaction pathways for aminocyclobutane formation are possible. In one pathway the [3,3]-sigmatropic rearrangement is the rate-limiting step and in the second pathway the electrocyclisation is rate limiting. Taken together, these reactions should facilitate the construction of fused heterocycles.

Synthesis of aminocyclobutanes through ring expansion of N-vinyl-beta-lactams.

Both eight-membered enamide rings and fused [4.2.0]aminocyclobutane-containing delta-lactams can be accessed from N-vinyl-beta-lactams. The eight-membered rings are made through a [3,3] sigmatropic rearrangement. At elevated temperature, the eight-membered lactam undergoes electrocyclization to furnish fused cyclobutane delta-lactams in a diastereoselective manner.