Preparation of Propargyl Hydroperoxides by Regioselective Oxidation of Allenic Zinc Reagents with Molecular Oxygen
摘要:
Treatment of allenic zinc reagents ((RRC)-R-1-C-2=C=C(R-3)ZnL), generated by the reaction of propargyl derivative ((RRC)-R-1-C-2(X)C=CH) with triorganozincates ((R3ZnLi)-Zn-3), under oxygen atmosphere in the presence of ZnCl2 and chlorotrimethylsilane afforded propargyl hydroperoxides ((RRC)-R-1-C-2(OOH)C=CR3) regioselectively. In this reaction, the use of ZnCl2 and chlorotrimethylsilane as additives is essential for the transformation of the initially generated allenic reagents to more reactive chlorozine species.
Highly regioselective gold-catalyzed formal hydration of propargylic <i>gem</i>-difluorides
作者:Jean-Denys Hamel、Tatsuru Hayashi、Mélissa Cloutier、Paul R. Savoie、Olivier Thibeault、Meggan Beaudoin、Jean-François Paquin
DOI:10.1039/c7ob02406a
日期:——
Herein, we report a highlyregioselective gold-catalyzed formal hydration of propargylic gem-difluorides. Not only does this transformation provide access to versatile fluorinated building blocks that were difficult or hardly possible to access beforehand, but it also represents a rare case of a highlyregioselective gold-catalyzed hydroalkoxylation of internal alkynes and puts forward the utility
α-Chiral alkyl primaryamines are virtually universal synthetic precursors for all other α-chiral N-containing compounds ubiquitous in biological, pharmaceutical, and material sciences. The enantioselective amination of common alkyl halides with ammonia is appealing for potential rapid access to α-chiral primaryamines, but has hitherto remained rare due to the multifaceted difficulties in using ammonia
Enantioselective Synthesis and Cross-Coupling of Tertiary Propargylic Boronic Esters Using Lithiation-Borylation of Propargylic Carbamates
作者:Benjamin M. Partridge、Laëtitia Chausset-Boissarie、Matthew Burns、Alexander P. Pulis、Varinder K. Aggarwal
DOI:10.1002/anie.201203198
日期:2012.11.19
Lithiation–borylation of propargyliccarbamates leads to tertiarypropargylicboronicesters in very high e.r., provided that ethylene glycol boronicesters are used. These versatile intermediates undergo a range of highly stereoselective transformations, including protodeboronation to give tertiary allenes and Suzuki–Miyaura cross‐couplings of tertiaryboron species leading to tetrasubstituted allenes
Formation of β-Oxo-<i>N</i>-vinylimidates via Intermolecular Ester Incorporation in Huisgen Cyclization/Carbene Cascade Reactions
作者:Qinxuan Wang、Jeremy A. May
DOI:10.1021/acs.orglett.0c03619
日期:2020.12.18
Unusual intermolecular trapping of esters by carbenes generated via a Huisgen cyclization/retroelectrocyclization/dediazotization cascadereaction is presented. β-Oxo-N-vinylimidates could be obtained in one step from propargyl carbonazidates. Mechanistic control experiments suggested reversible dipole formation by ester addition to the carbene, and nitrogen attack to the ester carbonyl was irreversibly
An efficient preparation of γ‐lactols and methylene‐γ‐lactols is described. Highly acid‐sensitive lactols are prepared in a concise manner by using a radicalcyclization of aluminumacetals. The precursors for the radical reactions are readily prepared from allyl or propargyl alcohols and α‐bromo acids. Functionalization of the resulting γ‐lactols and methylene‐γ‐lactols can be achieved following isolation