Das Spermin‐Alkaloid Chaenorpin

Abstract

The Spermine Alkaloid ChaenorpineChaenorpine (1) was isolated from Chaenorhinum minus (Scrophnlariaceae). Its structure elucidation was achieved on the basis of chemical degradation and spectroscopic mcasurements in comparison to the known alkaloid chaenorhine (2). Structure 1 displays the absolute configuration. (Fig. 1 ) auf, auch sind sie im DC eindeutig voneinander trennbar.Einen Einblick in die Skelett-Strukturunterschiede von Chaenorhin (2) und Chaenorpin (1) geben die NMR-Spektren von 1.

Facile Synthesis of 5‐Substituted 1H‐Tetrazoles Catalyzed by Tetrabutylammonium Hydrogen Sulfate in Water

“…5‐(3‐(Trifluoromethyl)phenyl)‐1 H ‐tetrazole (2i): White solid; mp: 156–157 °C (155–156 °C). IR (KBr, cm −1 ): 3200–2300 (br, NH), 3083, 1600, 1561, 1492, 1460, 906, 810, 763.…”

“…In order to overcome these disadvantages, new pathways have been developed, such as using a stoichiometric amount of inorganic salts and transition metal complexes as catalysts. In addition, various catalysts including AlCl 3 , Pd(OAc) 2 /ZnBr 2 , Pd‐(PPh 3 ) 4 , and Zn(OTf) 3 were also used for this purpose. However, these catalytic processes have limitations in separation, recovery, and reusability of the catalyst.…”

Synthesis of 5‐substituted 1H‐tetrazoles using a recyclable heterogeneous nanonickel ferrite catalyst

“…[10] Later, a dramatic procedure involving stoichiometric amounts of Zn(II) salts was reported under reflux in H 2 O. [11] Other recent developments include the synthesis of 5substituted 1H-tetrazoles under solvent-free conditions, [12] and the use of various catalysts such as Cu 2 O, [13] BF 3 ÁOEt 2 , [14] Pd(OAc) 2 / ZnBr 2 , [11] Yb(OTf) 3 , [15] Zn(OTf) 3 , [16] AlCl 3 , [17] CuSO 4 , [18] Pd(PPh 3 ) 4 , [19] TMSN 3 /TABF [12] and boron azides. [20] However, a drawback of these homogeneous catalytic processes is the difficulty in separation and recovery of the catalysts.…”