From `/usr/share/X11/locale/en_US.UTF-8/Compose`:

    ...
    <Multi_key> <less> <apostrophe>     : "‘"   U2018 # LEFT SINGLE QUOTATION MARK
    <Multi_key> <apostrophe> <less>     : "‘"   U2018 # LEFT SINGLE QUOTATION MARK
    <Multi_key> <greater> <apostrophe>  : "’"   U2019 # RIGHT SINGLE QUOTATION MARK
    <Multi_key> <apostrophe> <greater>  : "’"   U2019 # RIGHT SINGLE QUOTATION MARK
    <Multi_key> <less> <quotedbl>       : "“"   U201c # LEFT DOUBLE QUOTATION MARK
    <Multi_key> <quotedbl> <less>       : "“"   U201c # LEFT DOUBLE QUOTATION MARK
    <Multi_key> <greater> <quotedbl>    : "”"   U201d # RIGHT DOUBLE QUOTATION MARK
    <Multi_key> <quotedbl> <greater>    : "”"   U201d # RIGHT DOUBLE QUOTATION MARK
    ...
    <Multi_key> <minus> <minus> <minus> : "—"   U2014 # EM DASH
    ...

I genuinely do not understand how compose-lacking ɪᴍᴇs continue to see use—so much more of the full unicode spec is trivially available to you… even quite intuitively.

All the best,

-HG