We report herein an enantioselective acyl transfer protocol via electrophile activation. The reaction cascade sequence encompasses dinuclear zinc-catalyzed asymmetric Michael addition, intramolecular cyclization, and retro-Claisen reaction, which leads to a step- atom-economic approach variety of protected cyclic tertiary α-hydroxyketones in good yields with excellent enantioselectivities (24 e...

A transition-metal-free and base-promoted one-pot reaction of ynones with 2-aminobenzonitriles is described. The was initiated through sequential aza-Michael addition/intramolecular annulation to afford various multisubstituted 4-aminoquinolines 4-amino-1,8-naphthyridines in good excellent yields. Operational simplicity, high atom-economy broad substrate scope makes this protocol more attractiv...

silica ferric hydrogensulfate is an efficient heterogeneous catalyst for the cyclization of 2- aminochalcones to the corresponding 2,3-dihydroquinolin- 4(1h)-ones. this intramolecular aza michael reaction was carried out in high yields using chalcones bearing of electron donating and electron withdrawing groups. the catalyst is reusable without significant decreases in its activity after four t...

We present a general model for understanding the stereochemical course of intramolecular Michael reactions. We show that the addition of β-ketoester enolates to α,β-unsaturated esters and imides bearing adjacent stereocenters (X, Y = H, Me, OR) leads to high levels of asymmetric induction. Reinforcing and nonreinforcing stereochemical relationships are evaluated from the syn and anti reactant d...

A new short strategy to prepare the spiroketal fragment of calyculins is presented. A novel Seyferth–Gilbert type homologation of hindered lactols to the corresponding alkynes has been achieved for the first time. The spirocyclization was achieved efficiently via a DIHMA (double intramolecular hetero-Michael addition) process of this hindered ynone. The spirocyclization rate is not dependent on...

An efficient synthesis of novel 2,3-dihydro-4H-pyrido[1,2-a]pyrimidin-4-ones has been reported. Inexpensive and readily available substrates, environmentally benign reaction condition, and product formation up to quantitative yield are the key features of this methodology. Products are formed by the aza-Michael addition followed by intramolecular acyl substitution in a domino process. The polar...