= Solution
The analogous N-oxide rearrangement uses the carbon next to nitrogen that most readily supports addition and rearomatization. In <isoquinoline> this is C1. Thus replace the quinolin-2-yl group of D by isoquinolin-1-yl:
$$
\boxed{\text{2-phenyl-3-(isoquinolin-1-yl)chromen-4-one}.}
$$
The ynone-to-chromone atom mapping is unchanged. The change is \b[attachment at isoquinoline C1], rather than copying quinoline numbering and assigning an isoquinolin-2-yl carbon substituent at the nitrogen position.
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