Date: 16 Av 5586
From: Rabbi Moshe Sofer
To: Rabbi Asher
A community wishes to build a new synagogue while the old one's dome is structurally weakened, raising the prohibition against demolishing a synagogue before its replacement is completed. The Chasam Sofer permits proceeding by having the community purchase a room as an interim synagogue through an irrevocable sale, satisfying the requirement of Siman 152 before touching the old building.
Source: Shu"t Chasam Sofer OC §34