[{_id:"Doc1","name":"john","comment":"alpha; alpha lima alpha bravo golf"},{_id:"Doc2","name":"fonz","comment":"foxtrot alpha bravo fonz; zulu"},{_id:"Doc3","name":"zoltan","comment":"golf alpha bravo zoltan; alpha bravo delta; lambda alpha"}]

db.collection.find({$expr:{$regexMatch:{input:"$comment",regex:{$concat:["alpha bravo (?!","$name",")"]}}}})