Catalytic Enantio- and Diastereoselective Cyclopropanation
of 2‑Azadienes for the Synthesis of Aminocyclopropanes Bearing
Quaternary Carbon Stereogenic Centers
posted on 2019-08-29, 19:03authored byXinxin Shao, Steven J. Malcolmson
We report the catalytic
enantio- and diastereoselective preparation
of aminocyclopropanes by the cyclopropanation of terminal and (Z)-internal 2-azadienes with donor/acceptor carbenes derived
from α-diazoesters. The resulting cyclopropanes bear quaternary
carbon stereogenic centers vicinal to the amino-substituted carbon
and are formed as a single diastereomer in up to 99:1 er and 97% yield
with 0.5 mol % of Rh2(DOSP)4 and only 1.5 equiv
of the diazo reagent. Transformations with internal azadienes afford
cyclopropanes with three contiguous stereogenic centers.