Regioselective addition of Grignard reagents to <i>N</i>-acylpyrazinium salts: synthesis of substituted 1,2-dihydropyrazines and Δ<sup>5</sup>-2-oxopiperazines
作者:Valentine R St. Hilaire、William E Hopkins、Yenteeo S Miller、Srinivasa R Dandepally、Alfred L Williams
DOI:10.3762/bjoc.15.8
日期:——
The regioselective addition of Grignardreagents to mono- and disubstituted N-acylpyrazinium salts affording substituted 1,2-dihydropyrazines in modest to excellent yields (45-100%) is described. Under acidic conditions, these 1,2-dihydropyrazines can be converted to substituted Δ5-2-oxopiperazines providing a simple and efficient approach towards their preparation.
Preparation of <i>N</i>-Alkyl 2-Pyridones via a Lithium Iodide Promoted <i>O</i>- to <i>N</i>-Alkyl Migration: Scope and Mechanism
作者:Sarah Z. Tasker、Michael A. Bosscher、Christina A. Shandro、Erica L. Lanni、Keun Ah Ryu、Gregory S. Snapper、Jarrad M. Utter、Bruce A. Ellsworth、Carolyn E. Anderson
DOI:10.1021/jo3015424
日期:2012.9.21
An efficient and inexpensive LiI-promoted O- to N-alkyl migration of 2-benzyloxy-, 2-allyloxy-, and 2-propargyloxypyridines and heterocycles is reported. The reaction produces the corresponding N-alkyl 2-pyridones and analogues under green, solvent-free conditions in good to excellent yields (30 examples, 20–97% yield). This method has been shown to be intermolecular and requires heat and lithium cation
Heteroaryl-fused pyrazolo derivatives and methods for using the same
申请人:Arora Nidhi
公开号:US20050203091A1
公开(公告)日:2005-09-15
Compounds of the formula I:
where A, B, X, Y, Z, k, R
1
, R
2
and R
3
are those defined herein, and compositions comprising the same. The present invention also provides methods for preparing compounds of formula I and using the same in treating p38 mediated disorders in a patient.
Compounds having the formula I wherein A, R
1
, R
2
, R
3
, R
4a
, R
4b
, R
4c
, R
5
, R
6
, R
7a
, R
7b
, Ar
1
, R
c
, R
d
, R
e
, R
f
, X, n and p are as defined herein are Hepatitis C virus NS5b polymerase inhibitors. Also disclosed are compositions and methods for treating an HCV infection and inhibiting HCV replication.
Regioselective Reduction of 3-Substituted <i>N</i>-Acylpyrazinium Salts toward the Synthesis of 1,2-Dihydropyrazines
作者:Alfred L. Williams、Valentine R. St. Hilaire、Tina Lee
DOI:10.1021/jo202498r
日期:2012.4.20
The regioselectivereduction of 3-substituted N-acylpyrazinium salts with n-Bu3SnH has been developed for the synthesis of 3-substituted 1,2-dihydropyrazines in yields of 56–94%. Substitution of the pyrazinium salts with electron-donating groups favors the formation of the 1,2-isomers as a result of their better stability over the 1,6-isomers. Under mild acidic conditions, 3-methoxy substituted 1,2-dihydropyrazine