ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
In connection with the total synthesis of cytochalasans the cleavage of the macrocyclic system of cytochalasin D (3) was studied in order to gain useful relay compounds. Selective scission of the double bond in 19-position was achieved by controlled ozonolysis leading to compound 7 (Scheme 1). Treatment of 3 with OsO4 and subsequent acetylation gave the tetraacetoxy- and diacetoxy derivatives 8 and 9, respectively. Sharpless epoxidation of 3 yielded the mono-, di- and the two epimeric triepoxides 10, 11, 12, and 13, respectively.Further studies concerned the isomerization of the 6(12)-double bond to 6(7)-double bond by an allylic rearrangement. Treatment of 3 with mesylchloride and triethylamine led to 12-hydroxy-, 12-mesyloxy- and 12-chlorozygosporin (14, 16, and 17, resp.) (see Scheme 2). Epoxidation of 14 gave a mixture of the two epimeric 6,7-epoxides 21 and 23. Zn-reduction of 18 (the corresponding bromide of 17) led to zygosporin G (20).In order to convert a carbocyclic cytochalasan into a macrocyclic derivative, 3 was converted to 32 (Scheme 2). Treatment of 32 with H2O2 in acetic acid/chloroform or with phenylselenylperacid/H2O2 yielded the enollactone 33.Finally, 17,18-secocytochalasin D derivatives were prepared for the synthesis of unnatural analogs of macrolidic cytochalasans. The diol 26 was converted into the ketoaldehydes 38 and 40 and to the corresponding keto-acids 43 and 44 (Scheme 3), which were reduced to the ω-hydroxycarboxylic acids 45-48. Treatment of 47 with 2,2/-dipyridyldisulfide/triphenylphosphine/xylene gave probably the lactone 50.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19820650210
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