Quincunx of quads

Normal 6x6 sudoku rules apply. Place the digits 1-6 once each in every row, column and 2x3 box. Cells separated by a king's move (in chess) cannot contain the same digit. Digits in a circle must appear within the 2x2 of cells the circle touches. Digits may repeat if other rules allow. Clues outside the grid sum the digits along the indicated diagonal digits may repeat if other rules allow. Cells separated by a black dot has one digit double the other (1:2 ratio). Cells separated by a white dot are consecutive. No negative constraints.