A new route to functionalised hydroazulenes. Synthesis of (±)-confertin
作者:Michael Kennedy、M. Anthony McKervey
DOI:10.1039/c39880001028
日期:——
The advanced confertin intermediate (13) has been synthesised in 20% yield from a simple dihydrocinnamic acid precursor, the hydroazulene skeleton having been constructed by rhodium(II) mandelate-catalysed cyclisation–ring expansion of an α-diazoketone.
Pseudoguaianolides from intramolecular cycloadditions of aryl diazoketones: synthesis of (±)-confertin and an approach to the synthesis of (±)-damsin
作者:Michael Kennedy、M. Anthony McKervey
DOI:10.1039/p19910002565
日期:——
Rhodium(II) mandelate-catalysed cyclisation of alpha-diazoketones derived from 3-arylpropionic acids produces bicyclo[5.3.0]decatrienones, one of which has been used to synthesise an advanced (+/-)-confertin intermediate in six stages and 20% overall yield. The possibility of constructing intermediates for the synthesis of damsin-like pseudoguaianolides via catalysed diazoketone cyclisation is also examined and methods for the construction of polyfunctional 3-arylpropionic acids suitable for use as damsin precursors are presented.
The five-membered ring building blocks 2+3 are enantioselectively produced by conjugate addition of a chiral ligand-modified organocuprate to 2-methylcyclopent-2-enone (1) (chemical yield: 88%; e.e.: 88%) and successfully converted in a multi-step sequence, after final enantioselection by recrystallization of an appropriate intermediate, into the pseudoguaianolide (+)-confertin (5).
Novel and general entry into pseudoguaianolides. Formal and enantioselective synthesis of (+)-confertin
作者:Masafumi Ohtsuka、Yuki Takekawa、Kozo Shishido
DOI:10.1016/s0040-4039(98)01180-0
日期:1998.8
A novel and general access to pseudoguaianolide sesquiterpenoids has been developed by employing a diastereoselective acyl radical-mediated 7-endo-trigonal mode of cyclization as a key reaction step. The methodology has successfully been applied to the formal enantioselective synthesis of (+)-confertin. (C) 1998 Elsevier Science Ltd. All rights reserved.