A butyrolactone → 1,3-diol strategy for the obtention of Tolypothrix polyethers - Total synthesis of the Tolypothrix pentaether from enantiomerically enriched S-Glycidol [1]

Article abstract of DOI:10.1002/jlac.199719970805

Permethyl ether 1 from Tolypothrix conglutinata was synthesized following the retrosynthetic analysis of Scheme 1. According to it, we combined aldehyde 3 [prepared from S-glycidol (7); cf. Schemes 2, 3] and lactone 4 (also prepared from S-glycidol (7); cf. the preceding communication^[2] and Scheme 4) to the enantiopure and diastereopure trimethoxy lactone 2 (Scheme 5). The C=O group of this lactone was removed through the Criegee rearrangement of a derived lactol peroxonosylate (Scheme 6); thereby, the C-C=O bond of lactone 2 was replaced with complete retention of configuration by one C-OH bond of the resulting syn-configured diol 18. Protecting group manipulations (Schemes 6, 7) and oxidation of the resulting alcohol 21 to aldehyde 31 (Scheme 10) initiated the three final operations: C₂-homologation with Ph₃P=CH-CH=O (→ enal 32), tosyl hydrazone formation (→ 34), and reduction/concomitant C=C bond migration. They led to the target ether 1 as a 89:11 mixture with the CH=CH-richer ether 36. VCH Verlagsgesellschaft mbH, 1997.