Among its several embodiments, the present invention provides an improved process for the preparation of tetrahydrobenzothiepine-1,1-dioxide compounds; the provision of a process for preparing a diastereomeric mixture of tetrahydrobenzothiepine-1,1-dioxide compounds from a single diastereomer of such compounds; the provision of a process for the preparation of 3-bromo-2-substituted propionaldehyde compounds; and the provision of a process for the preparation of 3-thio-2-substituted propionaldehyde compounds.