Synthesis of the sedum and related alkaloids: A personal perspective

Significant recent contributions to the synthesis of the sedum alkaloids are discussed. Related compounds, such as pinidinol, porantheridine, dumetorine and the tetraponerines are also included. The syntheses are categorised according to the key motif or chemistry employed: isoxazolidines, metathesis, asymmetric aza-Michael, heterocycle lithiation, organocatalysis, aromatic heterocycles and chiral imines.     

New eco-friendly procedure for the synthesis of 4-arylmethylene-isoxazol-5(4H)-ones catalyzed by pyridinium p-toluenesulfonate (PPTS) in aqueous medium

In this work we describe a new, highly efficient method for the synthesis of 3-methyl-4-arylmethylidene-isoxazol-5(4H)-one derivatives by a three-component reaction between aromatic aldehydes, ethyl acetoacetate, and hydroxylamine hydrochloride under the influence by PPTS as a low-toxicity, inexpensive, commercially available and easy to handle catalyst. The advantages of this procedure are good yields, short reaction times, simplicity of implementation, and respect of the environment.     

Improved procedure for the enantioselective synthesis of dihydrooxazolo and dihydrothiazolo ring-fused 2-pyridones

Improved procedures to synthesize enantioselectively analogues of a peptidomimetic scaffold with high biological relevance have been developed. Experimental design led to a general method for the preparation of dihydrooxazolo ring-fused 2-pyridones in good yields and high enantiomeric purity. The knowledge gained from this was also used to improve the microwave-accelerated synthesis of dihydrothiazolo ring-fused 2-pyridones to give complete stereo retention and high yields.