だろうと[思「おも」]う => I think probably A N4
Sentence Endings
ようと[思「おも」]う => I think I will A N4
Causative, Passive, Volitional
かと[思「おも」]ったら/かと[思「おも」]うと => Athough A, B., As soon as I noticed A, B, almost immediately after A, B N2
Time, Situation
と[思「おも」]いきや => Even though A (was thought/expected), different result B N1
Contrast/Surprise
と([思「おも」]う、[言「い」]う、[考「かんが」]える) => That A N4
Particles