Allylic substitution of meso-1,4-diacetoxycycloalkenes in water with an amphiphilic resin-supported chiral palladium complex
Asymmetric π-allylic substitution of meso-1,4-diacet-oxycyclopentene and meso-1,4-diacetoxycyclohexene with various nucleophiles was performed with an amphiphilic polystyrene-polyethylene glycol) (PS-PEG) resin-supported chiral imidazoin-dolephosphine-palladium complex in water as a single reaction medium under heterogeneous conditions to give the corresponding 1-acetoxy-4-substituted cycloalkenes with up to 99% ee.
Chemoenzymatic synthesis of a versatile cyclopentenone: (+)-(3aS,6aS)-2,2-dimethyl-3aβ,6aβ-dihydro-4H-cyclopenta-1,3-dioxol- 4-one
The title cyclopentenone has been prepared by enzymatic resolution of cis-4-phenyloxy- and cis-4-(4-methoxyphenyloxy)-cyclopent-2-en-1-ol in isopropenyl acetate using Pseudomonas cepacia lipase. The use of a 4-methoxyphenyloxy-alcohol intermediate enabled the use of both enzymatically resolved enantiomers in the synthesis of the desired (+)-enone.
Biadatti, Thibaud,Esker, John L.,Johnson, Carl R.
p. 2313 - 2320
(2007/10/03)
Chemoenzymatic synthesis of trans-4,5-dihydroxycyclopent-2-enones: Conversion to D-1-deoxynojirimycin
(4R,5S)-trans-4,5-Bis(tert-butyldimethylsilyloxy)cyclopent-2-enone 8 and (4R,5S)-trans-4,5-di(benzyloxy)cyclopent-2-enone 20 are prepared by equilibration of the corresponding cis derivatives; enone 8 is transformed into the glucosidase inhibitor, D-1-deoxynojirimycin 14.
Johnson,Nerurkar,Golebiowski,Sundram,Esker
p. 1139 - 1140
(2007/10/02)
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