[Rutherford]

I see these reactions first time, so I need an explanation what is happening in each step.

[discodermolide]

I see these reactions first time, so I need an explanation what is happening in each step.

The first one is a diazotisation and substitution to give the alcohol, this reacts with acetic anhydride to give the ester.
Note that diazotisation of aliphatic amines is usually fraught with difficulty.

The second one is an amide formation with the acid chloride followed by a reduction with LiAlH4 to give the amine.

Perhaps you should study things more your level of expertise?

[Rutherford]

After the diazo compound is made, did you mean by substitution its hydrolysis?
Why is pyridine used in the second reaction?
"Perhaps you should study things more your level of expertise?" Don't understand.

[discodermolide]

After the diazo compound is made, did you mean by substitution its hydrolysis?
Why is pyridine used in the second reaction?
"Perhaps you should study things more your level of expertise?" Don't understand.

Yes it's hydrolysis.
Pyridine is used as a base to remove the HCl formed.

Well, these are simple well know reactions in O Chem. You should be aware of them, if you are not then your level of knowledge is not sufficient. I do not mean to be insulting, please understand that. You need to read a good textbook on O Chem, such as March's book, then you will gain a deeper insight.

[Rutherford]

I know that you aren't insulting, it's only that I started learning organic chemistry as a high school student few months ago. In the book there are only the most basic things, but I am not sure if I could examine a college book, still I have other things to study.
Thanks for the help.

[discodermolide]

I know that you aren't insulting, it's only that I started learning organic chemistry as a high school student few months ago. In the book there are only the most basic things, but I am not sure if I could examine a college book, still I have other things to study.
Thanks for the help.

OK I understand, ask away, no problem.
Make a college book your bedtime reading. I guarantee you will fall asleep vey quickly.