12 research outputs found
Self-Regeneration of Chirality with l‑Cysteine through 1,3-Dipolar Cycloadditions between Diazoalkanes and Enantiomerically Pure Thiazolines: Experimental and Computational Studies
Enantiopure 2-thia-4-azabicyclo[3.1.0]hexanes,
which can be considered
constrained cysteines, have been obtained from l-cysteine
by application of the “self-regeneration of chirality”
concept. The key intermediates are homochiral thiazolines that can
be prepared in multigram scale and react smoothly with a series of
diazoalkanes providing Δ<sup>1</sup>-pyrazolines except for
phenyldiazomethane that yield the isomeric Δ<sup>2</sup>-pyrazolines.
Nitrogen extrusion in Δ<sup>1</sup>-pyrazolines and further
reduction of the sulfinyl group yielded the target compounds in good
overall yield. Computational studies of the cycloaddition reaction
were used for determining the polarity of the process and explaining
the observed stereoselectivity. Additional topological studies were
employed for determining the influence of noncovalent interactions
in the stereochemical course of the reaction, which showed to be a
highly asynchronous concerted process