[間「あいだ」]/[間「あいだ」]に => During A, During A (before A is finished/over) N2
Time, Situation
中 => Throughout, all over, during the course of N5
Time
[最中「さいちゅう」] => In the middle of A N3
Time, Situation
[中心「ちゅうしん」]に => With A as the center N2
Miscellaneous