Ethylenediamine （H2NCH2CHeNH2） was found to be a highly effective catalyst for the condensation of aryl aldehydes with nitromethane （or nitroethane）. When 1%-2% （tool%） of ethylenediamine was used as the catalyst, the one-pot reaction of aryl aldehydes with nitromethane （or nitroethane） by refluxing for 3-10 h efficiently afforded various arylnitroalkenes la-ly in 85%-97% yields.
Yang Jianxin Dong Jing Lu Xia Zhang Qiang Ding Wei Shi Xiaoxin
A novel total synthesis of Mansouramycin B （1） was performed via 10 steps in 28% overall yield starting from the readily available and cheap salicylaldehyde. Two key steps of this total synthesis are noteworthy. The first one is base-promoted one-pot aerobic aromatization of N-tosyltetrahydroisoquinoline 6, the second one is oxidation of 5-hydroxy-3-methyl-isoquinoline 8 with iodobenzene diacetate [PhI（OAc）2].
A base-catalyzed ring-opening of 1-benzylisochromans 1 firstly produced 2-alkenylstilbenes 2, which then underwent a mild acid-catalyzed intramolecular cyclization to furnish 1,2-disubstituted indenes 3 in high yields. Subsequently, a base-catalyzed isomerization of the 1,2-disubstituted indenes 3 afforded the more stable 2,3-disubstituted indenes 4 in almost quantitative yields.
All of the four stereoisomers of methyl 4,5-epoxy-3-hydroxy-cyclohex-l-ene-carboxylate （la--ld） are useful chiral building blocks. Novel and efficient syntheses of these four epoxy chiral building blocks from naturally abun- dant （--）-shikimic acid （2） via cyclic sulfite intermediates are described in this article. The targeted compound （3R,4R,5S）-la was synthesized via four steps from （--）-shikimic acid in 79% overall yield. The other three targeted compounds （3S,4R,5S）-lb, （3S,4S,5R）-1c and （3R,4S,5R）-ld were synthesized via seven steps from （--）-shikimic acid in 56%, 64% and 65% overall yields, respectively.
Quan Na Nie Liangdeng Shi Xiaoxin Zhu Ruiheng Lu Xian
