60573-60-6Relevant academic research and scientific papers
Highly Selective and Catalytic Generation of Acyclic Quaternary Carbon Stereocenters via Functionalization of 1,3-Dienes with CO2
Chen, Xiao-Wang,Zhu, Lei,Gui, Yong-Yuan,Jing, Ke,Jiang, Yuan-Xu,Bo, Zhi-Yu,Lan, Yu,Li, Jing,Yu, Da-Gang
, p. 18825 - 18835 (2019/11/28)
The catalytic asymmetric functionalization of readily available 1,3-dienes is highly important, but current examples are mostly limited to the construction of tertiary chiral centers. The asymmetric generation of acyclic products containing all-carbon quaternary stereocenters from substituted 1,3-dienes represents a more challenging, but highly desirable, synthetic process for which there are very few examples. Herein, we report the highly selective copper-catalyzed generation of chiral all-carbon acyclic quaternary stereocenters via functionalization of 1,3-dienes with CO2. A variety of readily available 1,1-disubstituted 1,3-dienes, as well as a 1,3,5-triene, undergo reductive hydroxymethylation with high chemo-, regio-, E/Z-, and enantioselectivities. The reported method features good functional group tolerance, is readily scaled up to at least 5 mmol of starting diene, and generates chiral products that are useful building blocks for further derivatization. Systemic mechanistic investigations using density functional theory calculations were performed and provided the first theoretical investigation for an asymmetric transformation involving CO2. These computational results indicate that the 1,2-hydrocupration of 1,3-diene proceeds with high π-facial selectivity to generate an (S)-allylcopper intermediate, which further induces the chirality of the quaternary carbon center in the final product. The 1,4-addition of an internal allylcopper complex, which differs from previous reports involving terminal allylmetallic intermediates, to CO2 kinetically determines the E/Z- and regioselectivity. The rapid reduction of a copper carboxylate intermediate to the corresponding silyl-ether in the presence of Me(MeO)2SiH provides the exergonic impetus and leads to chemoselective hydroxymethylation rather than carboxylation. These results provide new insights for guiding further development of asymmetric C-C bond formations with CO2
Cyclopropylmethyl palladium species from carbene migratory insertion: New routes to 1,3-butadienes
Zhou, Lei,Ye, Fei,Zhang, Yan,Wang, Jianbo
supporting information; experimental part, p. 922 - 925 (2012/04/04)
Cyclopropylmethyl palladium species can be accessed by Pd-catalyzed reaction of either cyclopropyl N-tosylhydrazone with halide or N-tosylhydrazone with cyclopropyl halide. In both approaches migratory insertion of Pd carbene is the key process. These transformations constitute new approaches toward 1,3-butadiene derivatives.
The Thermal Ring Opening of 3,3-Disubstituted Cyclobutenes
Curry, Michael J.,Stevens, Ian D. R.
, p. 1391 - 1398 (2007/10/02)
The rates of the thermal unimolecular isomerisation of 3-t-butyl-3-methylcyclobutene and 3-methyl-3-phenylcyclobutene have been measured in the gas phase over the temperature ranges 158-190 deg C and 120-180 deg C, respectively.They are correlated by the Arrhenius expressions k = 1014.08 +/- 0.30exp(-150.8 +/- 2.5/RT) s-1 and k = 1012.50 +/- 0.12exp(-126.15 +/- 0.95/RT) s-1, respectively.The ratio of Z- to E-isomer of the butadienes formed has been measured both for these two and for the 3-methyl-3-R-cyclobutenes, where R = isopropyl, n-propyl, cyclopropyl, pentadeuterioethyl, 4-methoxyphenyl, 3-methoxyphenyl, and 4-cyanophenyl.In each case the proportion of Z-isomer formed is much larger than would be predicted on steric grounds.For the aryl compounds an attractive interaction during the formation of the Z-diene is proposed to account for its excess formation.For the alkyl substituents, a repulsive electronic interaction between the group and the developing remote double bond should be larger for methyl than for the other alkyl groups, accounting for the observed product ratios.The rates of isomerization of the 3-aryl-3-methylcyclobutenes at 161 deg C correlate with the LUMO of the aromatic ring.The conclusions are shown to apply to results which have been reported by other authors.
