99877-51-7Relevant articles and documents
Enantioselective Route to (-)-Chokol A
Suzuki, Toshio,Sato, Etsuko,Matsuda, Yasuyuki,Tada, Hitoshi,Koizumi, Satoko,et al.
, p. 1531 - 1533 (1988)
Stereoselective introduction of a methyl group to (3R)-2-methylcyclopentanone (2), followed by orthoester Claisen rearrangement provided the methyl ester (6) leading to (-)-chokol A (4).
A Short Synthesis of (-)-Chokol A
Urban, Ernst,Knuehl, Guido,Helmchen, Guenter
, p. 13031 - 13038 (2007/10/02)
(-)-Chokol A (10) was prepared in six steps (22 percent overall yield) via conjugate addition of a higher order cyanocuprate to the chiral 2-oxo-cyclopentenecarboxylate 2n.After deprotection by transesterification the enantiomerically pure β-ketoester 5 was obtained which was transformed by α-methylation and subsequent decarbethoxylation to the cyclopentanone derivative 8.Addition of methylcerium dichloride resulted in a mixture of 9a, 9b and 9c (78:16:6), from which the main diastereomer 9a was separated by MPLC.Finally desilylation of 9a achieved (-)-chokol A (10).
Stereoselective Synthesis of Steroids and Related Compounds, V. Synthesis of (+/-)-Chokol A by a Tandem Michael-Addition/Dieckmann Cyclization
Groth, Ulrich,Halfbrodt, Wolfgang,Koehler, Thomas,Kreye, Paul
, p. 885 - 890 (2007/10/02)
A total synthesis of (+/-)-chokol A (rac-12) was accomplished in five steps by starting from the α,β-unsaturated ester (E)-2 in an overall yield of 24percent.The key step of this synthesis is the tandem conjugate addition/Dieckmann cyclization of the cupr