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Approaches to the synthesis of cytochalasans. Part 8 . Further transformations and optical resolution of the tetrahydroisoindolinone subunit
Author(s) -
Schmidlin Tibur,
Wallach Daniel,
Tamm Christoph
Publication year - 1984
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19840670738
Subject(s) - chemistry , aldehyde , moiety , phosphonium , ylide , double bond , allylic rearrangement , hydroxylation , triol , phosphonium salt , alcohol , protecting group , stereochemistry , diol , organic chemistry , medicinal chemistry , salt (chemistry) , alkyl , catalysis , enzyme
The bicycle aldehyde 7 was prepared from the hydroxy ester 3 for the attachment of teh macrocyclic moiety of the cytochalasans. To protect the C(6),C(7)‐double bond the intermediates 8 , 9 and 13 were transformed into the epoxides 10 , 11 and 14 , respectively. Treatment of 10 and 11 with Al(i‐PrO) 3 gave the allylic alcohol 12 . Protection of the olefinic double bond was also effected by hydroxylation with OsO 4 . The triol 17 obtained from 3 , after acetalization of 18 , was oxidized to the aldehyde 20 . Attachment of the ylide of the phosphonium salt 1 to 20 gave 24 , an intermediate of proxiphomin ( 2 ). Removal of the C(6), C(7)‐diol group was achieved via the thiocarbonate 23 .