ISSN:
0009-2940
Keywords:
3,6-Alkanooxepine-4,5-dicarboxylic esters, optically active
;
Methanohydroazulenes
;
Photochemistry, solid-state
;
CD spectra
;
Absolute configuration
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Synthesis of Medium and Large Rings, XXXIII[1].-Optically Active 3a,6-Methanohydroazulenes via Chiral Induction of the Solid-State Photochemical Rearrangement of Bis(1,2:5,6-di-O-isopropylidene-α-D- and -α-L-glucofuranos-3-O-yl) 3,6-Hexanooxepine-4,5-dicarboxylateIrradiation of an aqueous suspension of the crystalline 3,6-hexanooxepine-4,5-dicarboxylic esters 2a and 2b affords the (3aS,6R,8aR)- and (3aR,6S,8aS)-methanohydroazulenes 3a and 4b in 54-58% yield with 92-93% de. Irradiation of an ethereal solution of 2a-2d on the other hand proceeds with low diastereoselectivity. The absolute configurations were established by X-ray structural analysis of the dimenthyl ester (+)-3d, comparison of CD spectra and chemical transformations. The origin of the high diastereoselectivity of the rearrangements 2a → 3a and 2b → 4b in the solid state is discussed on the basis of the X-ray structural analysis of the 3,6-heptanooxepine (-)-5a. Procedures for the removal of the chiral auxiliaries are described. Di-O-isopropylidene-α-L-glucofuranose is recycled in 95% yield.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19931260733
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