Common anionic nucleophiles such as those derived from inorganic salts have not been used for enantioselective catalysis because of their insolubility. Here, we report that merging hydrogen bonding and phase-transfer catalysis provides an effective mode of activation for nucleophiles that are insoluble in organic solvents. This catalytic manifold relies on hydrogen bonding complexation to render nucleophiles soluble and reactive, while simultaneously inducing asymmetry in the ensuing transformation. We demonstrate the concept using a chiral bis-urea catalyst to form a tridentate hydrogen bonding complex with fluoride from its cesium salt, thereby enabling highly efficient enantioselective ring opening of episulfonium ion. This fluorination method is synthetically valuable considering the scarcity of alternative protocols and points the way to wider application of the catalytic approach with diverse anionic nucleophiles.

At this stage, I've edited the manuscript for brevity and clarity. Queries are meant to draw your attention to edits, inconsistencies or issues that are unclear. If we just ask you to confirm edits are correct, a simple yes/ok between the brackets will do [Au:OK? Is this what you meant? Edits OK? yes]. If questions are asked, please rephrase/update the manuscript text when addressing queries, so that the message is conveyed to the reader (please do not just type your answer to our query unless it is unclear).As the reviewers noted, the manuscript is in very good shape and most comments and edits are fairly minor. However, there is an outstanding issue that must be addressed before we go forward. Figures 7 and 8 are currently referred to in the text in an alternating fashion (e.g. Figure 7A, 8A, 7B, 8B). This is against our style and might make that part of the manuscript difficult to follow for the reader owing to the need to refer to multiple figures at a time while reading the text. To clarify this issue, I recommend restructuring these figures. To do this, can you provide new chemdraw/PDFs with amended figures, including the following amendments: a. Merge Figures 7A and 8A to create a new 'Figure 7' that shows the methods of introducing CF2H at sp3-carbons. b. Merge figures 7B and 8B to make a new figure 8 that shows the main protocols of introducing CF2H at heteroaromatic carbons. 7C could be shown in it's own small figure (Figure 9) or could be added as panel B in the new figure 8. c. Amend the figure legends accordingly Apologies for another figure change but this is essential to keep the figure callouts in style and I think it will make the figures much easier for the reader to follow. I've asked the art editor to delay redrawing these particular figures until we receive these updated chemdraws/PDFs. If there are any issues with this change, please do let me know as soon as possible and we can discuss further.

Potassium fluoride (KF) is an ideal reagent for fluorination because it is safe, easy to handle and low-cost. However, poor solubility in organic solvents coupled with limited strategies to control its reactivity has discouraged its use for asymmetric C–F bond formation. Here, we demonstrate that hydrogen bonding phase-transfer catalysis with KF provides access to valuable β-fluoroamines in high yields and enantioselectivities. This methodology employs a chiral N-ethyl bis-urea catalyst that brings solid KF into solution as a tricoordinated urea-fluoride complex. This operationally simple reaction affords enantioenriched fluoro-diphenidine (up to 50 g scale) using 0.5 mol % of recoverable bis-urea catalyst.