A Novel Transformation of Esters to Alkynes with 1-Substituted Benzotriazoles
摘要:
Reactions of lithio benzotriazol-1-yl derivatives 2, 11, and 25 with aromatic and aliphatic esters 3, 12, and 26 gave alpha-(benzotriazol-1-yl) ketones 4, 13, and 27, respectively, in high yields. Alternatively, alpha-(benzotriazol-1-yl) ketones 22 can be accessed by the reaction of alpha-(benzotriazol-1-yl) esters 20 with Grignard reagents. Condensation of 4, 13, 22, and 27 with (p-toluenesulfonyl)hydrazine provided p-tosylhydrazones 5, 14, 21, and 28. Treatment of hydrazones 5, 21, and 28 with n-butyllithium in diethyl ether resulted in the elimination of the tosyl group, dinitrogen, and benzotriazolyl group to afford the corresponding acetylenes 9, 23, and 29 in good yields. When alpha-(benzotriazol-1-yl) 1-alpha-phenoxy hydrazones 14 were treated with methyllithium, n-butyllithium, or phenyllithium, alkynes 18 were obtained, in which phenoxy groups were replaced by the lithium reagents.
Mild and Phosphine-Free Iron-Catalyzed Cross-Coupling of Nonactivated Secondary Alkyl Halides with Alkynyl Grignard Reagents
作者:Chi Wai Cheung、Peng Ren、Xile Hu
DOI:10.1021/ol501087m
日期:2014.5.2
cross-coupling of nonactivated secondary alkylbromides and iodides with alkynyl Grignardreagents at room temperature has been developed. A wide range of secondary alkyl halides and terminal alkynes are tolerated to afford the substituted alkynes in good yields. A slight modification of the reaction protocol also allows for cross-coupling with a variety of primary alkyl halides.
Water as a Hydrogenating Agent: Stereodivergent Pd-Catalyzed Semihydrogenation of Alkynes
作者:Chuan-Qi Zhao、Yue-Gang Chen、Hui Qiu、Lei Wei、Ping Fang、Tian-Sheng Mei
DOI:10.1021/acs.orglett.9b00148
日期:2019.3.1
Palladium-catalyzed transfer semihydrogenation of alkynes using H2O as the hydrogen source and Mn as the reducing reagent is developed, affording cis- and trans-alkenes selectively under mild conditions. In addition, this method provides an efficient way to access various cis-1,2-dideuterioalkenes and trans-1,2-dideuterioalkenes by using D2O instead of H2O.
In(III)-Catalyzed Direct Regioselective Syntheses of 1-Naphthaldehyde Derivatives <i>via</i> a Hidden Aldehyde 1,3-Translocation and Disjointed CO<sub>2</sub> Extrusion
作者:Sabera Sultana、Gisela A. González-Montiel、Samjhana Pradhan、Hari Datta Khanal、Sagar D. Nale、Paul Ha-Yeon Cheong、Yong Rok Lee
DOI:10.1021/acscatal.1c00629
日期:2021.6.4
A highly regioselective annulation of 3-formylchromones with alkynes in the presence of indium triflate leads to the direct construction of diverse 1-naphthaldehyde derivatives. This one-pot de novo protocol features an unusual aldehyde 1,3-translocation and disjointed CO2 extrusion. This methodology is effective for the construction of structurally diverse 1-naphthaldehydes bearing chiral moieties
在三氟甲磺酸铟存在下,3-甲酰基色酮与炔烃的高度区域选择性环化可直接构建多种 1-萘醛衍生物。这种一锅从头协议具有不寻常的醛 1,3-易位和脱节的 CO 2挤出。该方法可有效构建具有手性部分和多芳烃的结构多样的 1-萘醛。这些萘醛可以进一步轻松地加工成各种官能团。密度泛函理论计算表明,这种 In(III) 催化的反应似乎是通过逐步脱芳环化、内酯化、环收缩以及最后排出 CO 2 进行的. 最有趣的是,醛易位不是通过醛的转座而是通过底物芳烃的骨架重排发生。
Copper-Catalyzed Intermolecular Alkynylation and Allylation of Unactivated C(sp<sup>3</sup>)–H Bonds via Hydrogen Atom Transfer
We describe Cu-catalyzed intermolecular alkynylation and allylation of unactivated C(sp3)–H bonds with singly occupied molecular orbital-philes (SOMO-philes) via hydrogen atom transfer (HAT). Employing N-fluoro-sulfonamide as a HAT reagent, a set of substituted alkene and alkyne compounds were synthesized in high yields with good regioselectivity and functional-group compatibility. Late-stage functionalization
with unfunctionalized ethers and amides was achieved in an atom-efficient and additive-free manner through the synergistic combination of photoredox and nickel catalysis. The protocol was effective with a wide range of internal alkynes, providing products in a highly selective fashion. Notably, the observed regioselectivity is complementary to conventional radical addition processes. Mechanistic investigations