We first investigated the preparation of sulfoximine-BCBs aiming for a 1-pot process. Initial studies used readily prepared N-Boc and N-silyl-methylsulfoximine derivatives. Conditions reported by Lindsay with methyl sulfones, using n-Bu2Mg as base for reaction with epichlorohydrin, were ineffective for both sulfoximine derivatives. N-Boc-sulfoximines also performed poorly using Li bases, giving incomplete conversion of the sulfoximine and mixtures of cyclopropanol and cyclobutanol products. The use of N-TBDPS-sulfoximine 1a allowed a wellbehaved deprotonation and reaction with epichlorohydrin (to form 3a, Scheme 1). Optimization of the base dosing showed that 3 additions of LDA, a total of 3.3 equivalents for 3 deprotonation steps, was most suitable to achieve the conversion of 1a to BCB sulfoximine 2a via cyclopropane 4a (see SI for further details). The individual steps were optimized, and a subsequent one-pot process formed 2a in a 75% yield (by 1 H NMR) and a 65% isolated yield on a 10 mmol scale.