Alcohols or Masked Alcohols as Directing Groups for C–H Bond Functionalization

Abstract

is currently a senior in the undergraduate chemistry department at The University of Texas. He has been working in the Dong Lab since summer of 2013 and will receive his bachelors degree in the spring of 2014. He expects to enter graduate school for organic chemistry in the fall of 2014. AbstractThis highlight review describes the recent progress in alcohol or masked alcohol-directed CH functionalization, which enables rapid access to a large array of complex structures. Given the ubiquity of the hydroxy group in organic chemistry, these types of transformations may have significant impacts on synthetic strategy design.

Sulfamate Esters Guide Selective Radical‐Mediated Chlorination of Aliphatic C−H Bonds

“…To our knowledge, there are no general strategies for aliphatic γ-C–H functionalization guided by a masked alcohol. [4,5] Herein described are the first experiments to demonstrate that sulfamate esters [6,7] can mediate 1,6-hydrogen-atom transfer (HAT) processes to guide the light-promoted chlorination of unactivatedγ-C(sp 3 )–H centers.…”

“…In traditional HLF processes, position selectivity arises based on formation of an intermediate nitrogen-centered radical that engages in a 1,5-HAT process [13] through a kinetically favored, six-membered transition state. [14] By contrast, we anticipate sulfamate esters may be capable of mediating 1,6-HAT processes, which are rare [15] as they are expected to proceed through seven-membered transition states, which are often kinetically disfavored. [16] We hypothesize that sulfamate esters enable 1,6-HAT because their elongated O–S and S–N bonds (∼1.58 Å) and compressed O–S–N bond angles (∼103°) [17] geometrically favor a seven-membered ring transition state for C–H abstraction.…”

Sulfamate Esters Guide Selective Radical‐Mediated Chlorination of Aliphatic C−H Bonds

“…Ah ydroxy group is attractive as ad irecting moiety because alcohols are common within readily available small molecules.T oo ur knowledge,t here are no general strategies for aliphatic g-C À Hf unctionalization guided by amasked alcohol. [4,5] Described herein are the first experiments to demonstrate that sulfamate esters [6,7] can mediate 1,6-hydrogen-atom transfer (HAT) processes to guide the light-promoted chlorination of unactivated g-C(sp 3 )ÀHc enters.…”

Meta‐Selective C−H Arylation of Aromatic Alcohols with a Readily Attachable and Cleavable Molecular Scaffold

“…[12] Our recent efforts have focused on the design of acetal-based scaffolds that feature pyridyl or quinolinyl groups for the functionalization of arene-based alcohols (Figure 1). [10] These scaffolds are readily covalently attached to alcohols, and when attached will induce ortho -selective Pd-catalyzed C–H alkenylations and arylations.…”