The hairless mutation of mice was caused by insertion of a murine leukemia virus. Starting with sequences flanking the provirus, a series of overlapping clones surrounding the viral integration site were obtained. By using a combination of sequencing, PCR, and exon-trapping techniques, the hairless gene was identified. It encodes a predicted protein of 1182 amino acids, incuding a potential zinc-finger domain.The expression patterns of the gene closely reflect the phenotype of animals carrying the hairless mutation.
The chemistry of
nitrogen-centered radicals (NCRs) has plentiful
applications in organic synthesis, and they continue to expand as
our understanding of these reactive species increases. The utility
of these reactive intermediates is demonstrated in the recent advances
in C–H amination and the (di)amination of alkenes. Synthesis
of previously challenging structures can be achieved by efficient
functionalization of sp2 moieties without prefunctionalization,
allowing for faster and more streamlined synthesis. This Review addresses
the generation, reactivity, and application of NCRs, including, but
not limited to, iminyl, aminyl, amidyl, and aminium species. Contributions
from early discovery up to the most recent examples have been highlighted,
covering radical initiation, thermolysis, photolysis, and, more recently,
photoredox catalysis. Radical-mediated intermolecular amination of
(hetero)arenes can occur with a variety of complex amine precursors,
generating aniline derivatives, an important class of structures for
drug discovery and development. Functionalization of olefins is achievable
in high anti-Markovnikov regioselectivity and allows access to difunctionalized
structures when the intermediate carbon radicals are trapped. Additionally,
the reactivity of NCRs can be harnessed for the rapid construction
of N-heterocycles such as pyrrolidines, phenanthridines, quinoxalines,
and quinazolinones.
Ruthenium-catalyzed isoquinolone syntheses with ample scope were accomplished through carboxylate assistance in environmentally benign water as a reaction medium. The high chemoselectivity of the ruthenium(II) carboxylate complex also set the stage for the direct use of free hydroxamic acids for annulations of alkynes.
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