ISSN:
0947-3440
Keywords:
syn β-Hydroxy ether
;
γ-Lactones
;
Polyethers
;
Polyalcohols
;
Polyol
;
Rearrangements
;
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The syntheses of two enantiopure skipped-chain pentaol building blocks 51 and 56 are described. They are based on a strategy which derives 1,3,7,9-tetraols from bis (γ-butyrolactones). Two equivalents of γ-lactone 17, readily available from L-glutamic acid, and one equivalent of the diiodoisobutene 22 furnished bis(γ-butyrolactone) trans,trans-21 stereoselectively in a single step. The same lactone, combined in a 2:1 ratio with the dibromoisobutene derivative 18, led in four steps and with good stereocontrol to the isomeric bis(γ-lactone) cis,trans-21. On the basis of the 1H- and 13C-NMR spectral data of these and other lactones it was possible to distinguish 1,3-cis- and 1,3-trans-disubstituted γ-lactones. Each of the bislactones was subject to a Criegee rearrangement of derived bis(peroxosulfonates) to give the diastereomerically pure 1,3,7,9-tetraols 26 and 31. The configuration of these tetraols was proven by the 13C-NMR shifts of the corresponding bis(acetonides) 27 and 32. Ozonolytic cleavage of the C=C bond of 27, reduction of the obtained ketone 28 to alcohol 29, acetonide rearrangement under thermodynamic control (→ 30), and fuctionalization of the liberated hydroxy group delivered the end group-differentiated 1,3,5,7,9-pentaol building block 51. It represents a segment of the polyol parts of the antibiotics roxaticin (52) and mycoticin (53). The oxidative cleavage of the C=C bond of bis(acetonide) 32 and chelation-controlled reduction of the resulting ketone 33 with Zn(BH4)2 furnished after acetonide migration and functionalization of the unprotected hydroxy group the all-syn-configured 1,3,5,7,9-pentaol building block 56. The latter compound should provide an entry into total syntheses of the naturally occurring poly(methyl ethers) 57 and 58.
Additional Material:
1 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jlac.199519950246
