With the feasibility of the synthesis established, we next addressed the development of hitherto unrealised asymmetric TDO cycloadditions. Investigations began with intermolecular (4+2) cycloadditions between indoles and enantioenriched thiophene S,S-dioxides equipped with inexpensive, readily available chiral substituents. We were delighted to find that reaction of indole (13a) with a TDO substituted with an acyl camphorsultam group 31 (14a, R 4 = 5-Cl) in CH2Cl2 at 0 °C afforded tricycle 15a as a single diastereoisomer in high yield. This method was tested on a range of substituted indoles, and showed broad functional group tolerance of both electron rich (e.g. methoxy) and electron poor substituents (e.g. ester, nitro, nitrile) at various positions around the indole ring, as well as useful functionality such as boronic esters and halides. N-substitution was also accommodated, with all tricyclic products isolated as single diastereomers in good to excellent yields (15b-15m, 68-93%). Variation of the thiophene S,S-dioxide was also well-tolerated, including a bicyclic TDO (15n-15p, 54-68%). With a view towards the proposed intermolecular cycloaddition approach to the Strychnos alkaloids, we further evaluated the use of 3-substituted indoles in this chemistry. Pleasingly, these reactions were also successful, albeit requiring higher temperatures to effect the cycloaddition due to the steric demand imposed by the additional indole substituent, affording cycloadducts 15q and 15r in 90% and 91% yields respectively, again as single diastereomers.