Lowpass Butterworth filter design (own poles' calculations)
Ok, I've solved this problem myself. I've used equation from this article mentioned in first post. I've just implement it in matlab not enough precise.

clc, clear all, close all;

%ANALOG BUTTERWORTH FILTER DESING
%https://engineering.purdue.edu/~ee538/AnalogFilterDesigns.pdf
%Butterworth LP with -3dB at fc and N order and G gain

wc = 1000;   %cut off frequency
N = 2;      %filter order
G = 1;      %filter gain 

%analog filter design
%poles and zeros 

%poles searching
for k = 0:N-1
   sk(k+1) = wc*exp(j*(pi/2))*exp(j*(2*k+1)*(pi/(2*N)));
end

[NUM,DEN] = zp2tf([],sk,G);
b0 = DEN(end)*G      %gain normalization  

Hs = tf(b0,DEN)

figure();
freqs(b0,DEN)
figure();
plot(sk./10^2, 'x')
xlim([-10,10]);
title('Poles placement in s-plane')


Many thanks for your help,
Maks