Symmetry-Assisted Synthesis of C2-Symmetric trans-α,α‘-Bis(hydroxymethyl)pyrrolidine and -piperidine Derivatives via Double Sharpless Asymmetric Dihydroxylation of α,ω-Terminal Dienes
摘要:
A new strategy has been developed for the synthesis of C-2-symmetric trans-alpha,alpha'-bis(hydroxymethyl)pyrrolidine and piperidine derivatives 1-3 starting from symmetric alpha,omega-terminal dienes 4-6. The double-asymmetric dihydroxylation (AD) reaction of 4-6 gave C-2-symmetric tetrols, which were converted in a four-step sequence to C-2-symmetric azacycloalkanes 17, 9, and 22, respectively. These azacycloalkanes were transformed into 1-3 in high enantiomeric excess (82% --> 98%ee). The double AD reaction proved to cause enantiomeric enhancement, even though the asymmetric induction for the first AD reaction is moderate. In addition, it was observed that the chromatography on silica gel of several C-2-symmetric azacycloalkanes (17, 20, and 22) of varying ee's resulted in marked enantiomeric fractionation.
Facile Route to 3,5-Disubstituted Morpholines: Enantioselective Synthesis of O-Protected <i>trans</i>-3,5-Bis(hydroxymethyl)morpholines
作者:Rajesh Dave、N. André Sasaki
DOI:10.1021/ol035998s
日期:2004.1.1
trans-3,5-Bis(benzyl/tert-butyldiphenylsilyloxymethyl)morpholines, promising candidates for the C-2-symmetric class of chiral reagents, were prepared with excellent optical purity. A key step in the synthesis is the coupling of a serinol derivative with 2,3-O-isopropylideneglycerol triflate or its equivalent. This methodology was extended to the synthesis of chiral trans-3-(benzyloxymethyl)-5-(tert-butyldiphenylsilyloxymethyl)morpholine, a potentially useful chiral building block.
Symmetry-Assisted Synthesis of <i>C</i><sub>2</sub>-Symmetric <i>trans</i>-α,α‘-Bis(hydroxymethyl)pyrrolidine and -piperidine Derivatives via Double Sharpless Asymmetric Dihydroxylation of α,ω-Terminal Dienes
A new strategy has been developed for the synthesis of C-2-symmetric trans-alpha,alpha'-bis(hydroxymethyl)pyrrolidine and piperidine derivatives 1-3 starting from symmetric alpha,omega-terminal dienes 4-6. The double-asymmetric dihydroxylation (AD) reaction of 4-6 gave C-2-symmetric tetrols, which were converted in a four-step sequence to C-2-symmetric azacycloalkanes 17, 9, and 22, respectively. These azacycloalkanes were transformed into 1-3 in high enantiomeric excess (82% --> 98%ee). The double AD reaction proved to cause enantiomeric enhancement, even though the asymmetric induction for the first AD reaction is moderate. In addition, it was observed that the chromatography on silica gel of several C-2-symmetric azacycloalkanes (17, 20, and 22) of varying ee's resulted in marked enantiomeric fractionation.
Tertiary amine-promoted enone aziridination: investigations into factors influencing enantioselective induction
作者:Alan Armstrong、Robert D.C. Pullin、Chloe R. Jenner、Klement Foo、Andrew J.P. White、James N. Scutt
DOI:10.1016/j.tetasy.2013.11.008
日期:2014.1
synthesised (up to 77% ee) via a chiral tertiary amine-promoted nucleophilic aziridination of α,β-unsaturated ketones utilising in situ generated N–N ylides (aminimines). A wide range of chiral tertiary amines were synthesised and evaluated, allowing structure–activity relationships to be drawn. The most efficient promoter for asymmetric aziridination, quinine, was assessed with several enones to ascertain