- The Silicon-Hydrogen Exchange Reaction: A Catalytic σ-Bond Metathesis Approach to the Enantioselective Synthesis of Enol Silanes
-
The use of chiral enol silanes in fundamental transformations such as Mukaiyama aldol, Michael, and Mannich reactions as well as Saegusa-Ito dehydrogenations has enabled the chemical synthesis of enantiopure natural products and valuable pharmaceuticals. However, accessing these intermediates in high enantiopurity has generally required the use of either stoichiometric chiral precursors or stoichiometric chiral reagents. We now describe a catalytic approach in which strongly acidic and confined imidodiphosphorimidates (IDPi) catalyze highly enantioselective interconversions of ketones and enol silanes. These "silicon-hydrogen exchange reactions"enable access to enantiopure enol silanes via tautomerizing σ-bond metatheses, either in a deprotosilylative desymmetrization of ketones with allyl silanes as the silicon source or in a protodesilylative kinetic resolution of racemic enol silanes with a carboxylic acid as the silyl acceptor.
- Zhou, Hui,Bae, Han Yong,Leutzsch, Markus,Kennemur, Jennifer L.,Bécart, Diane,List, Benjamin
-
supporting information
p. 13695 - 13700
(2020/08/24)
-
- 4-Arylcyclohexylamines
-
The invention relates to novel 4-hydroxymethyl(acyloxymethyl and methyl)-4-arylcyclohexylamines embraced by the formula SPC1 Wherein Ar is an aromatic ring selected from the group consisting of phenyl and naphthyl, each of which has from zero through three substituents independently selected from the group consisting of fluorine, chlorine, bromine, lower alkyl of one through three carbon atoms, lower alkoxy of one through three carbon atoms, and lower alkylthio of one through three carbon atoms; Z is selected from the group consisting of hydrogen, hydroxy and lower acyloxy of one through four carbon atoms; ? is a generic expression denoting cis and trans stereoconfiguration and mixtures thereof, with the proviso that when the stereoconfiguration of the linkage connecting the cyclohexane ring and CH2 Z is cis to the amino group, the linkage connecting the cyclohexane and Ar rings is trans, and vice versa; R1 is selected from the group consisting of hydrogen and lower alkyl of one through three carbon atoms; R2 is selected from the group consisting of hydrogen, lower alkyl of one through three carbon atoms, EQU1 WHEREIN N IS 2 THROUGH 5 AND Ar has the same meaning as above; R1 and R2 taken together with --N is a saturated heterocyclic amino radical selected from the group consisting of unsubstituted and substituted pyrrolidino, piperidino, hexamethylenimino, morpholino and piperazino; and pharmacologically acceptable acid addition salts thereof. It also relates to intermediates and processes for the preparation of the aforesaid novel compounds (I) and novel derivatives thereof. The administration to humans and animals of the novel compounds (I) depresses their central nervous systems and lowers their blood pressures.
- -
-
-
- Butyrophenones as hypotensive agents. Derivatives of 4 aryl 4 (hydroxymethyl)cyclohexylamine
-
The preparation of butyrophenone derivatives of 4 aryl 4 (hydroxymethyl) cyclohex 1 ylamines starting from the corresponding 4 cyano 4 phenylcyclohexan 1 ones is described. Substitution was varied in both rings; both isomers of 4 phenyl 4 (hydroxymethyl)cyclohex 1 ylamine were characterized. Those derivatives which carried p fluoro substitution on the butyrophenone exhibited hypotensive activity in the rat with diminished CNS activity compared to compounds lacking the hydroxymethyl group. The effect of substitution on the 4 aryl ring is discussed.
- Lednicer,Emmert,Rudzik,Graham
-
p. 593 - 599
(2007/10/06)
-