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The Application of [γ‐(Silyloxy)allylidene]ditin to the Efficient Synthesis of the Chromophore of the Neocarzinostatin Dihydroxycyclopentene‐Based Dienediyne Core
Author(s) -
Madec David,
Férézou JeanPierre
Publication year - 2006
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200500353
Subject(s) - chemistry , allylic rearrangement , synthon , sonogashira coupling , geminal , chromophore , alkyne , enediyne , palladium , trimethylsilyl , stereochemistry , acetylene , medicinal chemistry , organic chemistry , catalysis
1‐( tert ‐Butyldimethylsilyl)oxy‐3,3‐bis(tributylstannyl)propene ( 5 ), a versatile gem ‐dimetallic allylic synthon accessible through various synthetic routes, has been condensed with (trimethylsilyl)propiolaldehyde to give the fully functionalised acyclic vinyltin compound 9h , which is a precursor of the complex dihydroxycyclopentene sub‐unit of neocarzinostatin chromophore (NCS) 1 . Subsequent transformation into the geminal ( E )‐α‐chloro‐( Z )‐α‐iodovinylic intermediate 20 , followed by a palladium‐catalysed carbometallation/cyclisation reaction including in situ trapping with either (tributylstannyl)acetylene or the more functionalised 3,3‐diethoxy‐1‐(tributylstannyl)prop‐1‐yne delivered the corresponding alkyne‐substituted 4‐chloro‐1,2‐bis(silyloxy)cyclopent‐3‐enes 21 or 22 , respectively. Chlorocyclopentene 21 was subsequently easily transformed into the target dienediyne adduct 23 by Sonogashira condensation with trimethylsilylacetylene. This diastereoselective process is efficient with only six steps and an overall 26 % yield from the allylic ditin precursor 5 . More than just an NCS building block, the final acyclic dihydroxycyclopentene‐based dienediyne is also a seco analogue of the NCS chromophore. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)