Catalytic, Enantioselective Cycloaddition of Pyrrole-2-methides with Aldehydes toward a Synthesis of 2,3-Dihydro-1H-pyrrolizin-3-ols

An organocatalytic, highly enantioselective [6 + 2]-cycloaddition of 2-methide-2H-pyrroles with aryl acetaldehydes represents a novel and straightforward route toward densely substituted 2,3-dihydro-1H-pyrrolizin-3-ols, which were generated with good yields and high enantio- and diastereoselectivity. This one-step process involves a BINOL-phosphoric acid catalyzed reaction of 1H-pyrrole-2-carbinols with aryl acetaldehydes via the corresponding hydrogen-bonded, chiral 2-methide-2H-pyrroles.

An expedient microwave assisted regio- and stereoselective synthesis of spiroquinoxaline pyrrolizine derivatives and their AChE inhibitory activity

We report here an efficient protocol for the one-pot facile synthesis of spiro[indeno[1,2-b]quinoxaline-11,3′-pyrrolizine]heterocyclic scaffolds and their AChE inhibitory studies.

Model peptides containing the 3-sulfanyl-norbornene amino acid, a conformationally constrained cysteine analogue effective inducer of 310-helix secondary structures

Two model peptides containing the 3-benzylsulfanylnorbornene amino acid (NRB) was prepared. Theoretical calculations, spectroscopic and X-ray analyses confirmed that both NRB enantiomers possess a strong right-handed helicogenic effect.

Controlling Selectivity for Cycloadditions of Nitrones and Alkenes Tethered by Benzimidazoles: Combining Experiment and Theory

Herein we describe a combined experimental/theoretical study on the effects of substituents on regio- and stereoselectivity in intramolecular 1,3-dipolar cycloadditions of nitrones and alkenes tethered by benzimidazoles. By employing a large substituent at position R² or R³, complete selectivity was achieved for either the fused or bridged cycloadduct, respectively. In addition, these cycloadducts were formed as single diastereomers in all of the cycloadditions examined.