ketone-catalyzed asymmetric epoxidation reactions
DESCRIPTION
Ketone-Catalyzed Asymmetric Epoxidation Reactions. Application of Asymmetric Epoxidation in Natural Product Syntheses. MacDonald, F. et al Org. Lett 2000 , 2 , 2917. Yang, D. et al J.Org. Chem. 2000 , 65 , 2208-2217. Danishefsky, S. et al J. Org.Chem. 2001 , 66 , 4369-4378. - PowerPoint PPT PresentationTRANSCRIPT
Ketone-Catalyzed Asymmetric Epoxidation Reactions
Application of Asymmetric Epoxidation in Natural Product Syntheses
MacDonald, F. et al Org. Lett 2000, 2, 2917.
Yang, D. et al J.Org. Chem. 2000, 65, 2208-2217.
Danishefsky, S. et al J. Org.Chem. 2001, 66, 4369-4378.
Conditions for Converting Ketones into Dioxiranes
• H2O2 may also employed as a primary oxidant
Inductive Effects on Dioxirane Reactivity
Yang, D. et al J.Org. Chem. 2000, 65, 2208-2217.
First Generation Chiral Ketone Catalyst Design
4
Curci’s Chiral Ketones: ee’s were less that 20%
olefins investigated
Curci, R. et al Chem. Commun 1984, 156-156.
First Generation C2 Chiral Ketone Catalyst Design
trans-stilbene was the alkene substrate
Yang, D. et al J.Org. Chem. 2000, 65, 2208-2217.
Stereoelectronic Effect on C2 Symmetric Catalyst Activity
Yang, D. et al J.Org. Chem. 2000, 65, 2208-2217.
Stereoelectronic Effect on C2 Symmetric Catalyst Activity
Behar, V. et al Tetrahedron Lett. 2002, 43, 1943-1946.
Stereoelectronic Effect on C2 Symmetric Catalyst Activity
Tomioka, K. et al Tetrahedron Lett. 2002, 43, 631-633.
Stereoelectronic Effect on C2 Symmetric Catalyst Activity
Denmark, K. et al J. Org. Chem. 2002, 67, 3479-3486.
*ND = not determined
Chiral Ketones Derived from Sugars
Mechanistic Hypothesis
Epoxidation of Trisubstituted and trans-Substituted Alkenes
Shi, Y et al J. Am. Chem. Soc. 2002, 43, 631-633.
ee’s determined and compared to % conversion
Use of H2O2 as a Primary Oxidant
Mechanistic Hypothesis
12
Shi, Y et al Tetrahedron 2001, 57, 5213-5218.
Use of H2O2 as a Primary Oxidant
Mechanistic Hypothesis
12
Shi, Y et al Tetrahedron 2001, 57, 5213-5218.
Evaluation of Asymmetric Epoxidation with H2O2 as a Primary Oxidant
13Shi, Y et al Tetrahedron 2001, 57, 5213-5218.
ee’s determined and compared to % conversion
Mechanistic Hypotheses for Epoxidation Stereoselectivity
Shi, Y et al Tetrahedron 2001, 57, 5213-5218.
14
Singleton D. et al J. Am. Chem.Soc 2001,127, ASAP.
Inductive Effect on the Reactivity of the Chiral Ketone Catalyst
15Shi, Y et al Tetrahedron 2001, 57, 5213-5218.
Inductive Effect on the Reactivity of the Chiral Ketone Catalyst
Shi, Y et al J. Am. Chem. Soc. 2002, 124, 8792-8793.
* results obtained with catalyst 3
Design of a Catalyst which is More Suitable for cis Olefins
rationale for incompatibility with cis alkenes and terminal alkenes
Shi, Y et al J. Org. Chem. 2002, 67, 2435-2446.
Shi, Y et al J. Org. Chem. 2003, 68, 4963-4965.
Synthesis of Modified Catalyst
Typical Enantiomeric Excess Values Obtained from the Modified Catalyst
19Shi, Y et al J. Am. Chem. Soc. 2002, 67, 2435-2446.
Kinetic Resoluion of With Asymmetric Epoxidation
Shi, Y et al J. Am. Chem. Soc. 2005, ASAP.
Rationale for Kinetic Resolution of epoxides
Shi, Y et al J. Am. Chem. Soc. 2005, ASAP
Chiral Ketones Derived from D-Glucose
22
Shing et al Tetrahedron 2002, 58, 7545-7552.
Evaluation of a Chiral Ketone Derived from Glucose
23
Shing et al Tetrahedron 2002, 58, 7545-7552.
Evaluation of a Chiral Ketone Derived from Glucose
Shing et al Tetrahedron 2002, 58, 7545-7552.
Chiral Ketones Derived From L-Arabinose
Shing et al Tetrahedron 2003, 59, 2159-2168
Evaluation of a Chiral Ketone Derived From L-Arabinose
The Effect of pH on Catalyst Activity
Shing et al Tetrahedron 2003, 59, 2159-2168.
Chiral Ketones Derived from D-(-)-Quinic Acid
27
Shi, Y. et al 1997, 62, 8622-8623.
Chiral Ketones Derived from D-(-)-Quinic Acid
Shi, Y. et al 1997, 62, 8622-8623.
Chiral Ketones Derived from D-(-)-Quinic Acid
Shing et al Tetrahedron 2003, 59, 2159-2168.
29
Evaluation of Chiral Ketones Derived from D-(-)-Quinic Acid
30
Shing et al Tetrahedron 2003, 59, 2159-2168.
Asymmetric Epoxidation with Chiral Cyclohexanones
Roberts, S. M. J. Synth. Org. Chem. Jpn. 2002,60, 342-349.