Premium
Telescoping Reactions with Trifluorodiazoethane‐Derived Aza‐Wittig Reagents and Allenyl esters
Author(s) -
Zhang FaGuang,
Zeng JunLiang,
Tian YiQiang,
Zheng Yan,
Cahard Dominique,
Ma JunAn
Publication year - 2018
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201801171
Subject(s) - phosphine , reagent , wittig reaction , telescoping series , acetic acid , chemistry , diazo , organic chemistry , combinatorial chemistry , medicinal chemistry , catalysis , mathematics , mathematical analysis
Abstract A telescoping process involving the consecutive addition of four reagents (trifluorodiazoethane, phosphine, allenyl ester, and acetic acid) into a single reactor was developed for the novel functionalization of allenyl esters. First, new phosphazenes derived from trifluorodiazoethane and phosphines were generated and reacted with allenyl esters to give unexpected α‐iminophosphoranes through the creation of C=P, C=N, and C−H bonds at the α‐, β‐, and γ‐carbon atoms, respectively, of the allenyl esters. The α‐iminophosphoranes did not react with aldehydes in a classic Wittig reaction, but instead β‐enamino esters were obtained. The overall sequence of reactions offered a formal hydrohydrazonation of allenyl esters. The method was extended to other related diazo compounds and applied to the preparation of novel 5‐pyrazolone derivatives. Not only is the telescoping process described herein an effective approach for truncating the multistep synthesis, but also each step has been dissected to understand and support the reaction mechanisms.