Nickel-catalyzed cross-coupling of unactivated alkyl halides using bis(pinacolato)diboron as reductant
作者:Hailiang Xu、Chenglong Zhao、Qun Qian、Wei Deng、Hegui Gong
DOI:10.1039/c3sc51098k
日期:——
The use of bis(pinacolato)diboron as the terminal reductant allows the efficient Ni-catalyzed coupling of unactivated secondary and primary alkyl halides, generating the C(sp3)–C(sp3) coupling products in good yields. The mild catalytic conditions display excellent functional group tolerance, and good chemoselectivities which require only 1.5 equiv. of primary bromides for the coupling with secondary bromides. Preliminary mechanistic studies suggest that an in situ organoborane/Suzuki process is not likely. It was identified that the base and ligand have more profound impact on selecting this reductive coupling pathway. The good chemoselectivity appears to be evoked by the formation of Ni–Bpin catalytic intermediates, which demands matched sizes and reactivities of the alkyl halide coupling partners for optimal coupling efficiency.
[Object] To provide a reversibly thermochromic composition free from accidental discoloration by heat conducting from the opposite side writing surface or by self-heating due to quick writing; and also to provide a solid writing material and a writing ink composition comprising that composition.
[Means to solve the problem] A reversibly thermochromic composition comprising a combination of: (a) a reversibly thermochromic component capable of being discolored or decolored by heat and (b) a component for controlling heat conducting to the reversibly thermochromic component; and also a solid writing material and a writing ink composition comprising that composition.
Tunable directional color transition compositions and methods of making and using the same
申请人:Segan Industries, Inc.
公开号:US10168307B1
公开(公告)日:2019-01-01
Color change compositions that transition from a first to second color state upon application of an applied stimulus are provided. Also provided are substrates having the compositions on a surface thereof, as well as methods of making and using the compositions.
Compounds for reducing background color in color change compositions
申请人:Segan Industries, Inc.
公开号:US10570294B2
公开(公告)日:2020-02-25
Aspects of the invention include color change compositions having a color former and color developer composition that transitions from a first color state to a second color state upon application of an applied stimulus and an amount of a copolymer sufficient to eliminate background color of the color former and color developer composition during transition from the first color state to the second color state. Methods for preparing and devices employing the color change compositions of the invention are also described.