1817-49-8Relevant articles and documents
Highly diastereoselective sequential Michael-aldol reactions of methyl 2-chloro-2-cyclopropylideneacetate with Grignard reagents and aldehydes
Dalai, Suryakanta,Limbach, Michael,Zhao, Ligang,Tamm, Markus,Sevvana, Madhumati,Sokolov, Viktor V.,De Meijere, Armin
, p. 471 - 479 (2006)
Grignard reagents, especially isopropylmagnesium chloride, smoothly undergo Michael addition onto methyl 2-bromo- and 2-chloro-2-cyclopropylideneacetate (1-Cl), and the thus formed magnesium enolates are particularly efficiently trapped with aromatic aldehydes. This one-pot reaction provides highly substituted chlorohydrines, mostly in high yields (10 out of 18 examples with 72-92%) and as pure (2S*,3R*)-diastereomers (anti-aldols). These chlorohydrines can be transformed to Darzens-type α,β-epoxyesters in good yields, as demonstrated for one example. Georg Thieme Verlag Stuttgart.
Enantioselective addition of terminal alkynes to aldehydes catalyzed by a Cu(I)-TRAP complex
Asano, Yohsuke,Hara, Kenji,Ito, Hajime,Sawamura, Masaya
, p. 3901 - 3904 (2007)
The addition of terminal alkynes to aromatic aldehydes was carried out under mild conditions in the presence of a Cu-phosphine complex, which was prepared in situ from Cu(O-t-Bu) and TRAP chiral bisphosphine, to yield enantiomerically enriched propargyl alcohols with moderate enantioselectivities. Furthermore, according to stoichiometric reactions, the reaction presumably involves the addition of a TRAP-coordinated Cu(I) acetylide to an aldehyde.
Propargylation of CoQ0 through the Redox Chain Reaction
Pawlowski, Robert,Stodulski, MacIej,Mlynarski, Jacek
, p. 683 - 692 (2022/01/04)
An efficient catalytic propargylation of CoQ0 is described by employing the cooperative effect of Sc(OTf)3 and Hantzsch ester. It is suggested to work through the redox chain reaction, which involves hydroquinone and dimeric propargylic moiety intermediates. A broad range of propargylic alcohols can be converted into the appropriate derivatives of CoQ0 containing triple bonds in good to excellent yields. The mechanism of the given transformation is also discussed.
Enantioselective [3 + 2] annulation of 4-isothiocyanato pyrazolones and alkynyl ketones under organocatalysis
Wang, Wenyao,Wei, Shiqiang,Bao, Xiaoze,Nawaz, Shah,Qu, Jingping,Wang, Baomin
, p. 1145 - 1154 (2021/02/16)
An asymmetric [3 + 2] annulation reaction of 4-isothiocyanato pyrazolones with alkynyl ketones in the presence of an organic catalyst derived from a cinchona alkaloid under mild conditions is realized. This protocol provides unprecedented expeditious access to a wide range of optically active spiro[pyrroline-pyrazolones] with various electronic properties in high yields with good to excellent enantioselectivities.
Regioselective Iron-Catalysed Cross-Coupling Reaction of Aryl Propargylic Bromides and Aryl Grignard Reagents
Manjón-Mata, Inés,Quirós, M. Teresa,Bu?uel, Elena,Cárdenas, Diego J.
supporting information, p. 146 - 151 (2019/12/11)
An iron-catalysed Kumada-type cross-coupling reaction between aryl substituted propargylic bromides and arylmagnesium reagents has been developed. Propargylic coupling products were the main or only outcome, and propargyl/allene regioselectivity was shown to depend on the electronic nature of the substituents on the triple bond of the substrate and on the arylmagnesium halide. Best selectivities were observed when electron donating substituents were present in either reagent. The process is stereoespecific, occurs with configuration inversion and no carbon-based radicals seem to be involved in the mechanism. (Figure presented.).
