Herein, an efficient
and selective nickel-catalyzed dehydrogenation
of five- and six-membered N-heterocycles is presented. The transformation
occurs in the presence of alkyl, alkoxy, chloro, free hydroxyl and
primary amine, internal and terminal olefin, trifluoromethyl, and
ester functional groups. Synthesis of an important ligand and the
antimalarial drug quinine is demonstrated. Mechanistic studies revealed
that the cyclic imine serves as the key intermediate for this stepwise
transformation.
Herein,
we demonstrate a general and broadly applicable catalytic
cross coupling of methylene ketones and secondary alcohols with a
series of primary alcohols to disubstituted branched ketones. A simple
and nonprecious Fe2(CO)9 catalyst enables one-pot
oxidations of both primary and secondary alcohols to a range of branched gem-bis(alkyl) ketones. A number of bond activations and
formations selectively occurred in one pot to provide the ketone products.
Coupling reactions can be performed in gram scale and successfully
applied in the synthesis of an Alzehimer’s drug. Alkylation
of a steroid hormone can be achieved. A single catalyst enables sequential
one-pot double alkylation to bis-hetero aryl ketones using two different
alcohols. Preliminary mechanistic studies using an IR probe, deuterium
labeling, and kinetic experiments established the participation of
a borrowing-hydrogen process using Fe catalyst, and the reaction produces
H2 and H2O as byproducts.
Present review focuses on the recent progress achieved from 2017 to March 2021 using methanol as C1-alkylating agent. A series of novel metal-catalyzed hydrogen-borrowing processes have been developed using methanol....
Herein, nickel-catalyzed sustainable strategy for the synthesis of N-substituted pyrroles using butene-1,4-diols and butyne-1,4-diols with a series of aryl-, alkyl-, and heteroarylamines is reported. The catalytic protocol is tolerant of free alcohol, halide, alkyl, alkoxy, oxygen heterocycles, activated benzyl, and the pyridine moiety and resulted in up to 90% yield. Initial mechanistic studies involving defined nickel catalyst, determination of rate, and order of reaction including deuterium-labeling experiments were performed for pyrrole synthesis.
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