Enantioselectivity and catalysis improvements of Pseudomonas cepacia lipase with Tyr and Asp modification

2015 ◽  
Vol 5 (5) ◽  
pp. 2681-2687 ◽  
Author(s):  
Jing Li ◽  
Lei Yue ◽  
Chang Li ◽  
Yuanjiang Pan ◽  
Lirong Yang
Keyword(s):  
Catalytic Activity ◽  
Pseudomonas Cepacia ◽  
Secondary Alcohols ◽  
Pseudomonas Cepacia Lipase

A concise strategy to improve the p-nitrophenyl palmitate catalytic activity and enantioselectivity towards secondary alcohols of PcL is described.

The Baran Synthesis of Ingenol

2017 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Claisen Rearrangement ◽  
Secondary Alcohol ◽  
Cyclic Carbonate ◽  
The Other ◽  
Magnesium Bromide ◽  
Pseudomonas Cepacia ◽  
Pinacol Rearrangement ◽  
Pseudomonas Cepacia Lipase ◽  
La Jolla ◽  
Open Face

The early promise for the biological activity of the derivatives of ingenol 3 has been borne out by the clinical efficacy of the derived angelate, recently approved by the US Food and Drug Administration for the treatment of actinic keratosis. Phil S. Baran of Scripps La Jolla envisioned (Science 2013, 341, 878) a route to 3 based on a rearrange­ment of 2, available by the Pauson–Khand cyclization of the allenyl alkyne 1. One of the partners for the preparation of 1 was available following the Sugai (Synlett 1997, 1297) procedure, by the Claisen rearrangement of triethyl orthopro­pionate 5 with the propargyl alcohol 4 to give 6. Reduction delivered a racemic mix­ture of alcohols. On exposure of the mixture to vinyl acetate and Pseudomonas cepacia lipase, the undesired enantiomer was selectively acetylated to 7, leaving residual 8 of high ee. IBX was found by the Scripps group to be effective at oxidizing 8 without racemization. The other component of 1 was prepared from the inexpensive (+)-3-carene 10. Chlorination followed by ozonolysis delivered 11, that was reduced to the enolate, then alkylated with methyl iodide. Exposure to LiHMDS gave a new enolate, that was added to the aldehyde 9 to give 12. Addition of ethynyl magnesium bromide to the now more open face of 12 proceeded with high diastereoselectivity. Selective silylation of the secondary alcohol followed by silylation of the tertiary alcohol set the stage for the Pauson–Khand cyclization. Following the Brummond protocol, 1 was cyclized to 2. Methyl magnesium bro­mide was added, again to the more open face of the ketone, to give a new tertiary alco­hol. Exposure to stoichiometric OsO4 converted the more available alkene to the cis diol, that was protected as its cyclic carbonate 13. A central challenge in the total synthesis of the ingenanes is the construction of the “inside–outside” skeleton. This was achieved by the pinacol rearrangement of 13 with BF3•OEt2, to give 14. All that remained to complete the synthesis was selective oxidation. Allylic oxi­dation with stoichiometric SeO2 installed the secondary alcohol, that was acety­lated to give 15. The other secondary alcohol was then freed, and dehydrated with the Martin sulfurane, to give 16. A last allylic oxidation completed the synthesis of ingenol 3.

Catalytic oxidation of primary and secondary alcohols over a novel TCPP/Zn–Fe2O4@ZnO catalyst

RSC Advances ◽  
2015 ◽  
Vol 5 (121) ◽  
pp. 99640-99645 ◽  
Author(s):  
Mahdi Heidari-Golafzani ◽  
Mahboubeh Rabbani ◽  
Rahmatollah Rahimi ◽  
Alireza Azad
Keyword(s):  
Catalytic Activity ◽  
Catalytic Oxidation ◽  
Heterogeneous Catalyst ◽  
High Efficiency ◽  
Secondary Alcohols

The catalytic activity of TCPP/Zn–Fe2O4@ZnO as a recyclable and high efficiency heterogeneous catalyst for oxidation of primary and secondary alcohols using H2O2as a green oxidant under reflux conditions in CH3CN was investigated.

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