| 主权项 |
1. An organo catalytic process for preparation of decanolides of Formula Ia with high enantioselectivity,wherein, R1,R2, R3 and R4 are independently selected from the group consisting of H, OH, substituted or unsubstituted (C1-C5) alkyl; or R2 and R3 may together form an epoxy ring; (-----) represents either single or double bond, (—) represents cis or trans position of the substituents R1 to R4; wherein the said process comprising the steps of:
i. enantioselective allylboration of aldehyde (1) in presence of allyldiisopinocamphenylborane at temperature in the range of −120° C. to −80° C. for 1-2 hours in non-polar organic solvents selected from the group consisting of diethyl ether, pentane, cyclopentane, benzene, toluene, 1,4-dioxane, chloroform, and mixtures thereof followed by treatment with NaOH and aqueous H2O2 to obtain chiral allylic alcohol (3); ii. protecting chiral allylic alcohol (3) as obtained in step (i) with TBS by treating with TBSCl, imidazole, in a polar aprotic solvents selected from the group consisting of DMF, DCM, THF, ethyl acetate, acetone, and DMSO to obtain compound (4) followed by Wittig reaction by reacting Wittig reagent. Ph3P═CHCO2Et in a polar aprotic solvents preferably THF to obtain corresponding α-β unsaturated ester; iii. reducing α-β unsaturated ester (5) as obtained in step (ii) in presence of DIBAL-H in toluene at temperature range −80° C. to −50° C. to obtain α,β-unsaturated aldehyde (6) followed by organocatalytic Jørgensen epoxidation of α,β-unsaturated aldehyde (6) in presence of a chiral bisaryl-silyl-protected pyrrolidine preferably bis(3,5-bis(trifluoromethyl)phenyl)trimethyl silyloxy)methyl]pyrrolidine in the range of 5% to 20% and hydrogen peroxide and polar aprotic solvents selected from the group consisting of DMF, DCM, THF, ethyl acetate, acetone, and DMSO at ambient temperature ranging between 25-35° C. for a period followed by reduction in presence of NaBH4 in lower alcohol selected from the group consisting of methanol, ethanol, n-propanol, iso-propanol, and n-butanol at temperature range −5° C. to 5° C. to obtain enantiomerically enriched epoxy alcohol compound (7); iv. stirring epoxy alcohol (7) in presence of triphenylphosphine, iodine and imidazole reagent in an organic solvent selected from the group consisting of diethyl ether, DMF, DCM, THF, ethyl acetate, acetone, acetonitrile, methanol, ethanol, and mixtures thereof followed by treatment with Zn and NaI in methanol to obtain allylic alcohol (9) and further protecting allylic alcohol (9) with MOM in presence of MOMCl, DIPEA in DCM solvent to obtain compound (10) followed by deprotection of TBS to afford MOM protected allylic alcohol (11); v. esterification of MOM protected allylic alcohol (11) with MOM protected carboxylic acid compound (12) in presence of EDCl and DMAP in a polar solvent DCM to obtain ester compound (13); and ring-closing metathesis of ester compound (13) with Grubbs second generation carbene complex, followed by deprotection of MOM to obtain Formula Ia. |
