Direct Access to Allenylphosphine Oxides via a Metal Free Coupling of Propargylic Substrates with P(O)H Compounds
摘要:
A direct and convenient approach for the coupling of propargylic substrates with diphenylphosphine oxide in the presence of Tf2O and 2,6-lutidine has been developed. The method provides a general approach for the construction of attractive allenylphosphoryl skeletons with high atom and step economy under metal free conditions.
Efficient Asymmetric Synthesis of Biologically Important Tryptophan Analogues via a Palladium-Mediated Heteroannulation Reaction
作者:Chunrong Ma、Xiaoxiang Liu、Xiaoyan Li、Judith Flippen-Anderson、Shu Yu、James M. Cook
DOI:10.1021/jo001679s
日期:2001.6.1
A novel and concise synthesis of optically active tryptophan derivatives was developed via a palladium-catalyzed heteroannulation reaction of substituted o-iodoanilines with an internal alkyne. The required internal alkyne 14a or 25 was prepared in greater than 96% de via alkylation of the Schöllkopf chiral auxiliary 19 employing diphenyl phosphate as the leaving group. The Schöllkopf chiral auxiliary
Synthesis of heterocycles. Construction of the 1-azabicyclo[2.2.1]heptyl system by sequential ring-closure of acyclic β-ammonio substituted radicals
作者:Ernest W Della、Andrew M Knill
DOI:10.1016/0040-4039(96)01231-2
日期:1996.8
Treatment of an irradiated solution of 1-methyl-1-(2-propynyl)-1-bis(2-phenylselenylethyl)ammonium iodide in tert-amyl alcohol with tributyltin hydride is found to be an effective procedure for the synthesis of 1,4-dimethyl-1-azoniabicyclo-[2.2.1]heptaneiodide. Attachment of a trimethylsilyl or phenyl substituent to the terminal carbon of the triple bond in the alkynyl salt leads to bridgehead-substituted
Syntheses of Seven-Membered Rings: Ruthenium-Catalyzed Intramolecular [5+2] Cycloadditions
作者:Barry M. Trost、Hong C. Shen、Daniel B. Horne、F. Dean Toste、Bernhard G. Steinmetz、Christopher Koradin
DOI:10.1002/chem.200401065
日期:2005.4.8
The Ru-catalyzed intramolecular [5+2] cycloaddition of cyclopropylenynes is investigated with respect to the regio- and diastereoselectivity as well as the functional group compatibility of the reaction. Evidence for the mechanism as occurring through a ruthenacyclopentene intermediate is elucidated from 1) the study of the diastereoselectivity of the cycloaddition; 2) the effect of variation of substituents
Highly Enantioselective Syntheses of Homopropargylic Alcohols and Dihydrofurans Catalyzed by a Bis(oxazolinyl)pyridine−Scandium Triflate Complex
作者:David A. Evans、Zachary K. Sweeney、Tomislav Rovis、Jason S. Tedrow
DOI:10.1021/ja011983i
日期:2001.12.1
Lewisacid promoted reactions of allylsilanes and allenylsilanes provide access to important building blocks for natural product synthesis. 1 For example, trimethylsilylallenes function as propargylic anion equivalents in aldehydeadditionreactions (eq 1, Path A).2 If the silicon center is sterically congested, the normal addition pathway is suppressed and functionalized dihydrofurans are produced
Synthesis of propargylic fluorides from allenylsilanes
作者:Laurence Carroll、M? Carmen Pacheco、Ludivine Garcia、V?ronique Gouverneur
DOI:10.1039/b610013a
日期:——
Allenylsilanes reacted at room temperature in acetonitrile with Selectfluor, an electrophilic fluorinating reagent, to give secondary propargylic fluorides in moderate to good yields; mechanistically, a side-product resulting from a 1,2-silyl shift testifies to the presence of a cationic intermediate.