Option Explicit
Sub test()
Dim plage As Range, derlig As Long, i As Long
Dim WbA As Workbook, WbB As Workbook
Set WbA = Workbooks.Open("A.xlsx")
With WbA.Sheets("Tableaux")
Set plage = .Range("b2:f6")
End With
Set WbB = ThisWorkbook
With WbB.Sheets("Synthèse")
derlig = .Range("b" & Rows.Count).End(xlUp).Row
For i = 4 To derlig
If .Cells(i, 2) = "Synthèse" Then plage.Copy .Cells(i + 1, 2)
Next i
End With
End Sub