Medium-sized-ring Nitrogen-containing Heterocycles

8 Medium-sized-ring Nitrogen-containing Heterocycles 

The reaetion of MBH adduet and alkyl nitrile to give ( )-allyl amides 671 in 72-83% yields via Ritter reaetion (MeSOsH, 110 °C, 5 h) has been achieved by 

9 Construction of Nitrogen Heterocycles Containing Two Nitrogen Atoms 

MBH adducts 713, synthesized from 2-cyclohexen-l-one, have been converted into the corresponding pyrazole derivatives 714 in 48- 57% yields. The oxidation of 714 with DDQ (2.0 equiv) in benzene at reflux temperature gave 

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Reductive cleavage of the N-N bond in bicyclic systems containing a ring junction hydrazine subunit presents a facile route to medium-sized heterocycles containing two or more nitrogen atoms and the subject was duly covered in CHEC-II(1996) <1996CHEC-II(8)747>. No substantial progress has been reported since its publication. 

Natural Products Containing Medium-sized Nitrogen Heterocycles Synthesized by Ring-closing Alkene Metathesis... 

A particularly useful general method for the synthesis of saturated nitrogen- and oxygen-containing partially unsaturated heterocycles, from 5-membered to medium ring-sized, is the Grubbs olefin metathesis applied, for example, to acyclic diaUcenyl-amines, as illustrated by syntheses of a dihydropyrrole and a tetrahydropyridine. ... 

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