Premium
Tandem Michael Addition/Aldol Reaction of Allenic Ketones with Alkyl Vinyl Ketones: Versatile Synthesis of 2‐Alkynyl 1,5‐Diketones, 4‐Alkynyl‐3‐hydroxycyclohexanones and 4‐Alkynylcyclohexenones
Author(s) -
Malhotra Deepika,
Liu LePing,
Hammond Gerald B.
Publication year - 2010
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201001161
Subject(s) - chemistry , diastereomer , aldol reaction , michael reaction , methyl vinyl ketone , ketone , alkyl , organic chemistry , nuclear magnetic resonance spectroscopy , reactivity (psychology) , medicinal chemistry , catalysis , medicine , alternative medicine , pathology
The reactivity of alkynylenolate was investigated in the reactions of allenic ketones and vinyl ketones. We found that different products could be obtained under different conditions. The tetrabutylammonium fluoride (TBAF)‐mediated Michael addition of allenic ketones to vinyl ketones gave 2‐alkynyl 1,5‐diketones as the product. Under stronger basic conditions, a tandem Michael addition/aldol reaction of the two starting materials occurred in one pot, and 4‐alkynyl‐3‐hydroxycyclohexanone could be isolated at low temperature, whereas 4‐alkynylcyclohexenones was obtained at room temperature. It should be noted that only one diastereoisomer of 4‐alkynyl‐3‐hydroxycyclohexanone was isolated from the reaction even when ethyl vinyl ketone was used as the Michael acceptor, as determined by 1 H and 13 C NMR spectroscopy. The configurations of the diastereoisomers were confirmed by NOESY spectroscopy.