ISSN:
0947-3440
Keywords:
Homoallyl alcohols, synthesis of
;
Lactones
;
Polyethers
;
1,3,5,7,…-Polyol, synthesis
;
Rearrangements
;
Tolypothrix
;
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Following the retrosynthetic plan of Scheme 1 the permethyl ether 1 from Tolypothrix conglutinata was synthesized from aldehyde 2 and the hydroxylated butyrolactone 3b. Each of these building blocks was obtained from a homoallyl alcohol, i. e. aldehyde 2 from homoallyl alcohol 5 (Scheme 3; 98.1% ee) and lactone 3b from homoallyl alcohol 30 (Schemes 10, 11; 97.7% ee). These alcohols, in turn, stemmed from the Ti(OEt)4/S-BINOL-mediated enantioselective addition of the β-substituted stannane 7 to hexanal (Scheme 3) and the Ti(OEt)4/R-BINOL-mediated enantioselective addition of the β-substituted stannane 31 to aldehyde 32 (Scheme 10), respectively. After O-methylation of hydroxy lactone 3b (Scheme 11), the resulting methoxy lactone 38 was condensed with aldehyde 2 by Larson's modification of the Peterson olefination to provide the γ-alkylidene lactone 39 as a 65:35 mixture of Z/E isomers (Scheme 12). Hydrogenation of this mixture gave the cis-configured γ-alkyl lactone 40 (Scheme 12). It was accompanied by no more than 5 mol-% of its trans isomer; this observation seems to imply the occurrence of butenolide 41 as an intermediate of this reaction. An oxidative degradation of lactone 40 via the Criegee rearrangement of a derived peroxonosylate provided the syn-diol 42 from where another three steps led to the target ether 1 (Scheme 13).
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jlac.199719970806
