217298-58-3Relevant academic research and scientific papers
Preparation of enantiomerically pure 4-alkyl-5-formyl-4-nitrocyclohex-1-enes from 5-glyco-4-nitrocyclohex-1-enes
Ballini,Bosica,Gil,Roman,Serrano
, p. 1773 - 1787 (2007/10/03)
Base-catalyzed (TMG, DBU or TEA) asymmetric Michael reactions between 5-glyco-4-nitrocyclohex-1-enes 1a or 1b and a number of mono- or α,β-disubstituted electron-deficient alkenes yielded, in all cases, adducts in which the sugar side-chain and the added group on C-4 of the cyclohexene ring showed a trans-relationship. Furthermore, some of the adducts have been used to prepare enantiomerically pure 4-alkyl-5-formyl-4-nitrocyclohex-1-enes by a two-step process involving base-catalyzed (NaOMe) deacetylation of their respective sugar side-chains and subsequent oxidative cleavage (NaIO4). When reactions of 1a or 1b with dimethyl maleate, dimethyl fumarate or methyl trans-4-oxopentenoate were carried out with DBU (instead of TMG) as catalyst, there was in situ elimination of nitrous acid.
Stereoselective Michael addition reactions of 5-glyco-4-nitrocyclohex- 1-enes
Areces,Gil,Higes,Roman,Serrano
, p. 8557 - 8560 (2007/10/03)
Michael additions of 5-glyco-4-nitrocyclohex-1-enes (2 and 3) proceeded in a stereoselective way, leading in each case to single adducts in which the electron-deficient alkenes add on the C-4 of the cyclohexene rings, in a trans mode to the adjacent, sterically demanding, sugar side-chain. When dimethyl maleate or dimethyl fumarate and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) were used, there was in situ elimination of nitrous acid, and the product consisted in a 1:1 mixture of the epimeric α,β-unsaturated esters 7.
