Advantageous Syntheses of Diazo Compounds by Oxidation of Hydrazones with Lead Tetraacetate in Basic Environments
摘要:
Varied sensitive diazo compounds 3 are produced efficiently and safely in 3-6 g quantities by oxidation (eq 1) of hydrazones 1 at -78 degrees C with lead tetraacetate (2) in triethylamine/chloroform, N-methylmorpholine/dimethylformamide, tetramethylguanidine (8)/dimethylformamide, and tetramethylguanidine/methylene chloride, respectively, upon use of appropriate workup and handling techniques. New and improved nonhazardous procedures have been developed for preparing and handling hydrazones 1 from aldehydes and ketones in reactions with excess hydrazine.
Submonomer synthesis of peptoids containing <i>trans</i>-inducing <i>N</i>-imino- and <i>N</i>-alkylamino-glycines
作者:Carolynn M. Davern、Brandon D. Lowe、Adam Rosfi、Elon A. Ison、Caroline Proulx
DOI:10.1039/d1sc00717c
日期:——
The use of hydrazones as a newtype of submonomer in peptoid synthesis is described, giving access to peptoid monomers that are structure-inducing. A wide range of hydrazones were found to readily react with α-bromoamides in routine solid phase peptoid submonomer synthesis. Conditions to promote a one-pot cleavage of the peptoid from the resin and reduction to the corresponding N-alkylamino side chains
Switch in Selectivity for Formal Hydroalkylation of 1,3‐Dienes and Enynes with Simple Hydrazones
作者:Leiyang Lv、Lin Yu、Zihang Qiu、Chao‐Jun Li
DOI:10.1002/anie.201915875
日期:2020.4.16
anti-Markovnikov addition is obtained by changing to a ruthenium catalyst, thus providing direct and efficient access to homoallylic products exclusively. Isotopic substitution experiments indicate that no reversible hydro-metallation across the metal-π-allyl system occurred under ruthenium catalysis. Moreover, this protocol is applicable to the regiospecific hydroalkylation of the distal C=C bond of 1,3-enynes
作者:Wei Wei、Xi-Jie Dai、Haining Wang、Chenchen Li、Xiaobo Yang、Chao-Jun Li
DOI:10.1039/c7sc04207h
日期:——
Natural availability of carbonyl groups offers reductive carbonyl coupling tremendous synthetic potential for efficient olefin synthesis, yet the catalytic carbonyl cross-coupling remains largely elusive. We report herein such a reaction, mediated by hydrazine under ruthenium(II) catalysis. This method enables facile and selective cross-couplings of two unsymmetrical carbonyl compounds in either an
羰基的自然可用性为有效的烯烃合成提供了还原性羰基偶联的巨大合成潜力,但催化羰基的交叉偶联仍然很难实现。我们在本文中报道了在钌(II)催化下由肼介导的这种反应。该方法能够以分子间或分子内的方式使两种不对称羰基化合物容易且选择性地交叉偶联。此外,该化学物质可容纳多种底物,在温和的反应条件下以良好的官能团耐受性进行,并产生化学计量的良性副产物。重要的是,KO t Bu和双齿膦dmpe的共存对于这种转化至关重要。
Palladium-catalyzed hydroalkylation of methylenecyclopropanes with simple hydrazones
作者:Jinzhong Yao、Zhangpei Chen、Lin Yu、Leiyang Lv、Dawei Cao、Chao-Jun Li
DOI:10.1039/d0sc01221a
日期:——
A palladium-catalyzed hydroalkylation reaction of methylenecyclopropanes via highly selective C–C σ-bond scission was achieved under mild conditions, in which simple hydrazones served as carbanion equivalents. This method featured good functional group compatibility, affording high yields of C-alkylated terminal alkenes.
Palladium‐Catalyzed Defluorinative Alkylation of
<i>gem</i>
‐Difluorocyclopropanes: Switching Regioselectivity via Simple Hydrazones
作者:Leiyang Lv、Chao‐Jun Li
DOI:10.1002/anie.202102240
日期:2021.6
can completely switch the reaction selectivity to give the alkylated α-fluoroalkene skeletons (branched selectivity). The unique reactivity of hydrazones that enables analogous inner-sphere 3,3′-reductive elimination driven by denitrogenation, as well as the assistance of steric-embedded N-heterocyclic carbene ligand, are the key to switch the regioselectivity. A wide range of hydrazones derived from