Asymmetric Total Synthesis of (−)-Indicol by a Carbene Cyclization–Cycloaddition Cascade Strategy
作者:Sze Kui Lam、Pauline Chiu
DOI:10.1002/chem.200700838
日期:2007.11.26
The first totalsynthesis of a secodolastane, (-)-indicol, has been accomplished. The key reaction is a rhodium(II)-mediated carbene cyclization-cycloaddition cascade, by which the core bicyclo[5.4.0]undecane skeleton was assembled. In this one-pot reaction, a domino series of transformations resulting in the construction of three sigma bonds and three stereocenters was realized in good yield.
Disclosed herein are novel prostaglandin I.sub.2 (PGI.sub.2) derivatives exhibiting excellent in vivo duration and activities, said derivatives being represented by the general formula: ##STR1## wherein R.sub.1, X, R.sub.2 and R.sub.3 are as defined herein.
Highly effective asymmetrichydrogenation of β-ketophosphonates in the presence of Ru–(S)-SunPhos as catalyst was realized; good to excellent enantioselectivities (up to 99.9% ee) and excellent diastereoselectivities (96:4) were obtained.
Synthesis of ring-contracted, 25-nor-6,5-spiroketal-modified avermectin derivatives
作者:Peter T. Meinke、Stephen P. O'Connor、Helmut Mrozik、Michael H. Fisher
DOI:10.1016/s0040-4039(00)91896-3
日期:1992.2
A versatile, high yielding strategy for the synthesis of ring-contracted, 25-nor-6,5-spiroketal-modified avermectin analogs (7A - 7N) bearing diverse substituents at C24 is described. In addition, an efficient Pb(OAc)4-mediated oxidative cleavage to produce the key intermediate, aldehyde 3, is presented.