In standard IPA transcriptions there is no syllable separator (the dot). Therefore, if you look at dictionaries, particularly British dictionaries, that employ the IPA such as Oxford Dictionaries, the Macmillan or the Collins, you will see
/kɑːˈtuːn/ or /kɑː(r)ˈtuːn/
The stress mark (ˈ) is placed before the stressed syllable.
Some dictionaries, especially American dictionaries, indicate syllables; this is often marked in the headword. This information is often included to indicate how a word might be separated across lines. The Merriam Webster, for instance, shows this:
The pronunciation is indicated by a kind of modified IPA (with diacritics) and the hyphen is employed as a syllable separator:
Dictionary.com does not employ IPA, but instead uses respelling; it uses the hyphen the same way and stress is indicated by boldfacing.
Dictionaries that stick to the full IPA do not generally indicate syllable division whereas those that do not might include syllable division markers.