Cycloaddition reactions of alkenes

Lewis acid- and/or Lewis base-catalyzed [3+2] cycloaddition reaction: synthesis of pyrazoles and pyrazolines

“…Electron withdrawing groups on the dipolarophile normally favor an interaction of the LUMO of the dipolarophile (electron poor olefin/alkyne) with HOMO of the diploe that leads to the formation of the new bonds, whereas electron donating groups on the dipolarophile normally favor the inverse of this reaction. 2 In continuation of our efforts in the development of various aspects of Baylis-Hillman reaction, 3 and utilityt of the adducts therof in the organic synthesis, 4 herein we report the use of Baylis-Hillman adducts for C-N bond formation 5 to result in the heterocyclic ring formation affording corresponding pyrazolines (Scheme 1). Amongst the two DABCO and InCl 3 , the reaction was more facile with DABCO to afford products in good yields and in shorter time.…”

Congeneric Lantibiotics from Ribosomal In Vivo Peptide Synthesis with Noncanonical Amino Acids

“…A Cu I -catalyzed Huisgen 1,3-dipolar cycloaddition (click reaction) [16] was performed with Blia(Met28Hpg) according to protocols described previously (Table S3 in the Supporting Information). [17] Synthetic coupling to the Blia peptide was achieved with 1-azido-1-deoxy-b-d-glucopyranoside and azido-fluorescein as shown by HR-ESI-MS (Figure 1).…”

Environmentally Benign Lewis Acid Promoted [2+3] Dipolar Cycloaddition Reactions of Nitrile Imines with Alkenes in Water

“…While a few Lewis acid promoted 1,3-dipolar cycloaddition reactions [8,9] have been successfully employed in aqueous media where the Lewis acid was composed of silver [10] or lithium, [11] other aqueous based 1,3-dipolar cycloaddition reactions utilized prefabricated 1,3-dipoles. [12] Furthermore, in some cases where 1,3-dipoles were generated in situ, micellar catalysts were often used under basic reaction conditions.…”