The stereoselective total syntheses of pectinolides A, B, and C
摘要:
The stereoselective total synthesis of pectinolide B has been accomplished for the first time along with total syntheses of pectinolides A and C. MacMillan alpha-hydroxylation and Sharpless asymmetric dihydroxylation reactions are involved in generating the three stereogenic centers. Other important transformations in the synthesis are Z-selective Still-Gennari olefination, selective benzylation of the homoallylic alcohol, and a one-pot MOM deprotection followed by lactonization leading to all three pectinolides A-C being synthesized from a common intermediate. Pectinolides A, B, and C were synthesized from n-hexanal in 19, 20, and 18 steps with overall yields of 8.8%, 6.72%, and 9.2%, respectively. (C) 2014 Elsevier Ltd. All rights reserved.
First stereoselective total synthesis of pectinolide A
摘要:
The enantioselective synthesis of bio-active 5,6-dihydro-alpha-pyrone, pectinolide A, has been achieved in 10 steps in good overall yield. Of the three stereogenic centres, the C-5/C-6 vic-diol was obtained using dia-stereo- and enantioselective Brown hydroxyl crotylation, while the C-3' stereocentre was created by Jacobsen hydrolytic kinetic resolution method. (C) 2011 Elsevier Ltd. All rights reserved.
[reaction: see text] The rhodium(I)-catalyzed methylenation of ketones using trimethylsilyldiazomethane proceeds to give the corresponding alkenes in good yields (60-97%). The use of an excess of 2-propanol and 1,4-dioxane as a solvent were instrumental to obtain the desired alkenes in high yields. Superior results were achieved with the rhodium(I)-catalyzed methylenation in comparison with the standard