Direct Access to 6/5/7/5- and 6/7/5/5-Fused Tetracyclic Triterpenoids via Divergent Transannular Aldol Reaction of Lanosterol-Derived Diketone
نویسندگان
چکیده
منابع مشابه
Vinylogous anionic processes in the formation and interconversion of tetracyclic ring systems.
Tandem oxy-Cope and transannular vinylogous aldol reactions and/or vinylogous retro-aldol, conjugate addition, and transannular vinylogous aldol reactions transformed some tricyclic vinyl enones into fused tetracycles under basic conditions. Mesylates derived from similar tetracyclic products underwent efficient skeletal reorganization via transannular ring-opening but then different modes of t...
متن کاملOne-pot synthesis of tetracyclic fused imidazo[1,2-a]pyridines via a three-component reaction
A novel three-component reaction has been developed to assemble biologically and pharmaceutically important tetracyclic fused imidazo[1,2-a]pyridines in a one-pot fashion utilizing readily available 2-aminopyridines, isatins and isocyanides. The three-component coupling proceeds through the Groebke-Blackburn-Bienaymé reaction followed by a retro-aza-ene reaction and subsequent nucleophilic reac...
متن کاملSynthesis of fused tetracyclic spiroindoles via palladium-catalysed cascade cyclisation.
Efficient palladium-catalysed cascade cyclisation to form spiroindoles is developed. Treatment of indoles bearing a propargyl chloride side chain at the 3-position with various external nucleophiles in the presence of a catalytic amount of Pd2(dba)3·CHCl3/dppb and Cs2CO3 in THF gives fused tetracyclic spiroindoles in moderate to good yields.
متن کاملAsymmetric aldol reaction via memory of chirality.
Asymmetric aldol reactions of α-amino acid derivatives via memory of chirality were developed. Chiral oxazolidones with contiguous tetra- and trisubstituted chiral centers were obtained in 78-94% ee by the asymmetric aldol reaction followed by intramolecular acylation.
متن کاملThe first direct and enantioselective cross-aldol reaction of aldehydes.
The first enantioselective catalytic direct cross-aldol reaction that employs nonequivalent aldehydes has been accomplished using proline as the reaction catalyst. Structural variation in both the aldol donor (R1 = Me, n-Bu, Bn, 91 to >99%) and aldol acceptor (R2 = I-Pr, I-Bu, c-C6H11, Et, Ph, 97-99% ee) are possible while maintaining high reaction efficiency (75-88% yield). Significantly, this...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: The Journal of Organic Chemistry
سال: 2013
ISSN: 0022-3263,1520-6904
DOI: 10.1021/jo402005b