Synthesis of Bicyclic Guanidines via Cascade Hydroamination/Michael Additions of Mono-N-acryloylpropargylguanidines

Abstract

A cascade silver(I)-catalyzed hydroamination/Michael addition sequence has been developed to deliver highly substituted bicyclic guanidines. This transformation gives rise to geometrically and constitutionally stable ene–guanidines and generates a remote stereocenter with moderate to high diastereoselectivity.

Activation of Primary Amines by Copper(I)-Based Lewis Acid Promoters in the Solventless Synthesis of Secondary Propargylamines

“…Many synthetic methods have been developed for the synthesis of different classes of heterocycles [1][2][3][4][5][6][7][8][9][10] starting from propargylamines. At the same time, propargylamines are direct precursors of propargylureas that can undergo silver-or gold-catalyzed cycloisomerization to produce a series of other nitrogen-containing heterocyclic compounds.…”

Asymmetric Organocatalytic 1,4‐Addition Reactions Starting from Enals with gem‐Difluoroalkyl Side Chains

“…Based on the above observations and the related reports,21b,22a,b,e,23 plausible pathways for the domino reaction are proposed in Scheme . In the presence of a copper catalyst and a base, anionic intermediate ( E ) and its tautomers [e.g., ( E′ )] are generated by addition of propargylic amine 2 onto carbodiimide 1 and subsequent coordination/deprotonation.…”

“…It is noteworthy that exclusive formation of product 3 was observed under these conditions, likely because the amino group at the o‐ haloaryl ring was more favourable for the cyclisation process than the other amino groups 21b,23. This may be ascribed to its suitable acidity, which leads to the easier formation of corresponding anionic intermediate ( E ).…”

Copper‐Catalyzed Reaction of Secondary Propargylamines with Ethyl Buta‐2,3‐dienoate for the Synthesis of 1,6‐Dihydropyridines

“…It is well known, that secondary propargylamines can undergo additions to a number of heteroallenes allowing to assemble a variety of heterocycles through the subsequent transition metal‐catalyzed or electrophile‐mediated cyclizations . Considering this, we decided to investigate an addition of propargylamine 1a to ethyl buta‐2,3‐dienoate ( 12 ) in an attempt to overcome the limitation arisen from the inability of former to react with electron‐deficient alkyne 11c (Table ).…”