Total Syntheses of (−)-Grandinolide and (−)-Sapranthin by the Sharpless Asymmetric Dihydroxylation of Methyl trans-3-Pentenoate: Elucidation of the Stereostructure of (−)-Sapranthin

• Published in: Chemistry : a European journal Vol. 4; no. 11; pp. 2342 - 2352
• Main Authors: Harcken, Christian, Brückner, Reinhard, Rank, Elisabeth
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 02.11.1998; WILEY‐VCH Verlag; Wiley
• Subjects: Asymmetric synthesis; Chemistry; Chemistry, Multidisciplinary; Dihydroxylations; Physical Sciences; Rearrangements; Science & Technology; Structure elucidation; γ-lactones; HEMIACETAL PHEROMONE; ACID; NATURAL-PRODUCTS; dihydroxylations; GAMMA-BUTYROLACTONES; asymmetric synthesis; DIENOLATE ANIONS; LACTONES; BUTENOLIDES; rearrangements; CHEMISTRY; gamma-lactones; structure elucidation; BUG BIPRORULUS-BIBAX; BLASTMYCINONE
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/(SICI)1521-3765(19981102)4:11<2342::AID-CHEM2342>3.0.CO;2-Q

The commercially available title ester (1) was converted into the phytochemicals (−)‐grandinolide (3) and (−)‐sapranthin (4) through trans‐selective alkylations of the “dianions” derived from enantio‐enriched β‐hydroxy‐γ‐lactones and excess LDA. Lactone 2 was obtained from 1 through an asymmetric dihydroxylation (1 step, 78 % ee). Through alkylation, the “dianion” of 2 gave 3. The OH group of lactone 2 was also inverted. Deprotonation of the new lactone with excess LDA and alkylation led to 4 whose stereoformula was thereby revised and completed.