FIELD : medicine; pharmaceuticals.SUBSTANCE : invention relates to a compound represented by formula (I) or a pharmaceutically acceptable salt thereof. In formula (I) P is hydrogen or group PR, selected from following formulas : a) -C(=O)-PR0, b) -C(=O)-PR1, g) -C(=O)-O-PR2, h) -C(=O)-N(-K)(PR2), i) -C(=O)-O-L-O-PR2, l) -C(PR3)2-O-C(=O)-PR4, m) -C(PR3)2-O-C(=O)-O-PR4, v) -C(PR3)2-PR6, y) -C(PR3)2-N(-K)-C(=O)-O-PR2, z) -P(=O)(-PR8)(-PR9) and ab) -PR11, A1 is CR1AR1B; A2 is CR2AR2B; A3 is CR3AR3B, S or O; each of A4 independently represents CR4AR4B; number of heteroatoms among atoms forming a ring, which consists of A1, A2, A3, A4, nitrogen atom adjacent to A1, and a carbon atom adjacent to A4, is 1 or 2; group represented by formula represents a group represented by formula , values of other radicals are given in claim. Invention also relates to individual compounds. EFFECT : technical result is obtaining novel compounds of formula (I) inhibiting activity of cap-dependent endonuclease and which can be used in treating influenza virus.11 cl, 2 dwg, 40 tbl, 39 ex