Naming secondary amine IUPAC system

$\ce{CH3NHCH(CH3)CH2CH3}$  

Should this be named as 2-(N-methyl)butanamine or 2-(methylamino)butane?


In other words, do we name the compound as 'alkanamine' or treat amino group as a substituent of butane?




It should be N-methyl-2-butanamine. Amine is treated as a functional group attached. So we write it as alkanamine as it is the only functional group here.


![enter image description here](https://i.stack.imgur.com/yyZxi.png)


Image source: [ChemSpider](http://www.chemspider.com/Chemical-Structure.99670.html)


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