Site-predictable and chemoselective C–H bond functionalization
reactions offer synthetically powerful strategies for the step-economic
diversification of both feedstock and fine chemicals. Many transition-metal-catalyzed
methods have emerged for the selective activation and functionalization
of C–H bonds. However, challenges of regio- and chemoselectivity
have emerged with application to highly complex molecules bearing
significant functional group density and diversity. As molecular complexity
increases within molecular structures the risks of catalyst intolerance
and limited applicability grow with the number of functional groups
and potentially Lewis basic heteroatoms. Given the abundance of C–H
bonds within highly complex and already diversified molecules such
as pharmaceuticals, natural products, and materials, design and selection
of reaction conditions and tolerant catalysts has proved critical
for successful direct functionalization. As such, innovations within
transition-metal-catalyzed C–H bond functionalization for the
direct formation of carbon–carbon bonds have been discovered
and developed to overcome these challenges and limitations. This review
highlights progress made for the direct metal-catalyzed C–C
bond forming reactions including alkylation, methylation, arylation,
and olefination of C–H bonds within complex targets.
We discuss recent advances in the applications of cycloruthenated complexes in organic synthesis, comprising C–H activation, chiral-at-metal catalysis, Z-selective olefin metathesis, transfer hydrogenation, enantioselective cyclopropanations and cycloadditions.
Although there is an abundance of methods for the enantioselective synthesis of 2-isoxazolines and 2-isoxazolin-5-ones, relatively few of these approaches have been reported when these heterocycles bear fully substituted stereocenters. In this review, we will detail the methods that have been used to successfully accomplish these challenging asymmetric trans-formations and give insights into their importance, such as allowing access to unique three-dimensional chemical space. The limitations of the currently known reactions will be discussed, as well as highlighting the future developments needed to advance the research field.
Although there is an abundance of methods for the enantioselective synthesis of 2-isoxazolines and 2-isoxazolin-5-ones, relatively few of these approaches have been reported when these heterocycles bear fully substituted stereocenters. In this minireview, we will detail the methods that have been used to successfully accomplish these challenging asymmetric transformations and give insights into their importance, such as allowing access to unique three-dimensional chemical space. The limitations of the currently known reactions will be discussed, as well as highlighting the future developments needed to advance the research field.
Although there is an abundance of methods for the enantioselective synthesis of 2-isoxazolines and 2-isoxazolin-5-ones, relatively few of these approaches have been reported when these heterocycles bear fully substituted stereocenters. In this minireview, we will detail the methods that have been used to successfully accomplish these challenging asymmetric transformations and give insights into their importance, such as allowing access to unique three-dimensional chemical space. The limitations of the currently known reactions will be discussed, as well as highlighting the future developments needed to advance the research field.
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