Asymmetric synthesis of 4′-C-benzyl-2′,3′-dideoxynucleoside analogues from 3-benzyl-2-hydroxy-2-cyclopenten-1-one
摘要:
Both enantiomers of the key intermediate, 2-benzyl-5-oxo-tetrahydro-furan-2-carboxylic acid were obtained by asymmetric oxidation of 3 -benzyl-2-hyd roxy-2-cyclopen ten- 1 -one with all ee >= 96%, using the tartaric ester/Ti(OiPr)(4)/t-BuOOH complex, and transformed to the corresponding 4'-substituted nucleoside analogues with up to 61% overall yield. (C) 2008 Elsevier Ltd. All rights reserved.
Asymmetric Synthesis of Tertiary 2-Substituted 5-Oxotetrahydrofuran-2-carboxylic Acids
摘要:
3-Substituted 1,2-cyclopentanediones 1 were transformed to 2-substituted 5-oxotetrahydrofuran-2-carboxylic acids 2 using a catalytic process with 0.2-0.3 equivalent of Ti(OiPr)(4)/tartaric ester/tBuO0H complex in up to 72% isolated yield and up to 94% ee. Different functional groups in the 3-alkyl substituent of 1 like, hydroxy, ether, Boc-amino and ester groups are tolerated. Boc-aminomethyl substitu.ents lead to beta-amino acid analogues and Boc-aminoethyl substituent to gamma-amino acid analogues as well as spiro-lactonelactams. A direct, two-step procedure for homocitric acid synthesis is described.