Hexafluoroisopropyl Sulfamate: A Useful Reagent for the Synthesis of Sulfamates and Sulfamides

Enantioselective Total Syntheses of (+)-Kasugamycin and (+)-Kasuganobiosamine Highlighting a Sulfamate-Tethered Aza-Wacker Cyclization Strategy

Here, we present the first enantioselective total syntheses of the natural products (+)-kasugamycin, a potent antifungal antibiotic, and (+)-kasuganobiosamine, a compound that results from the degradation of kasugamycin. Salient features of these syntheses include a second-generation enantioselective preparation of a kasugamine derivative (efficiency much improved relative to that of our first chiral-pool effort) and our laboratory's sulfamate-tethered aza-Wacker cyclization.

The Development of a Sulfamate-Tethered Aza-Michael Cyclization Allows for the Preparation of (-)-Negamycin tert-Butyl Ester

We present the first examples of intramolecular aza-Michael cyclizations of sulfamates and sulfamides onto pendant α,β-unsaturated esters, thioesters, amides, and nitriles. Stirring the substrate with catalytic quantities of the appropriate base delivers the product in good yield and excellent diastereoselectivity. The reactions are operationally simple, can be performed open to air, and are tolerant of a variety of important functional groups. We highlight the utility of this technology by using it in the preparation of a (-)-negamycin derivative.

Sulfamate-Tethered Aza-Wacker Strategy for a Kasugamine Synthon

We present our preparation of a kasugamine synthon, which proceeds in 14 steps from a literature epoxide. We expect that this kasugamine derivative can be used for the total syntheses of kasugamycin, minosaminomycin, and analogue antibiotics. A key step in the synthesis is our laboratory's sulfamate-tethered aza-Wacker cyclization.

Ring Opening of Aziridines by Pendant Sulfamates Allows for Regioselective and Stereospecific Preparation of Vicinal Diamines

The ring opening of aziridines by pendant sulfamates is a viable strategy for the rapid preparation of vicinal diamines. Our reaction is compatible with both disubstituted cis- and trans-aziridines; unsubstituted, N-alkyl, and N-aryl sulfamates engage effectively. In all cases examined, the cyclization reaction is perfectly regioselective and stereospecific. Once activated, the product oxathiazinane heterocycles can be ring opened with a diverse range of nucleophiles.

Covalent Tethers for Precise Amino Alcohol Syntheses: Ring Opening of Epoxides by Pendant Sulfamates and Sulfamides

We describe the development of the first ring opening of epoxides using pendant sulfamates and sulfamides. These reactions are promoted by a base and proceed under mild conditions to afford oxathiazinanes and cyclic sulfamides with excellent diastereoselectivity and regiocontrol. The reactions scale well, and the products serve as synthons for ring-opening reactions.

Sulfur(iv) reagents for the SuFEx-based synthesis of substituted sulfamate esters

Sulfur(vi) fluoride exchange chemistry has been reported to be effective at synthesizing valuable sulfur(vi) functionalities through sequential nucleophilic additions, yet oxygen-based nucleophiles are limited in this approach to phenolic derivatives. Herein, we report a new sulfur(iv) fluoride exchange strategy to access synthetically challenging substituted sulfamate esters from alkyl alcohols and amines. We also report the development of a non-gaseous, sulfur(iv) fluoride exchange reagent, N-methylimidazolium sulfinyl fluoride hexafluorophosphate (MISF). By leveraging the reactivity of the sulfur(iv) center of this novel reagent, the sequential addition of alcohols and amines to MISF followed by oxidation afforded the desired substituted sulfamates in 40-83% yields after two steps. This new strategy expands the scope of SuFEx chemistry by increasing the accessibility of underdeveloped -S(O)F intermediates for future explorations.

Kukhtin-Ramirez-Reaction-Inspired Deprotection of Sulfamidates for the Synthesis of Amino Sugars

Herein, we present a mild strategy for deprotecting cyclic sulfamidates via the Kukhtin-Ramirez reaction to access amino sugars. The method features the removal of the sulfonic group of cyclic sulfamidates, which occurs through an N-H insertion reaction that implicates the Kukhtin-Ramirez adducts, followed by a base-promoted reductive N-S bond cleavage. The mild reaction conditions of the protocol enable the formation of amino alcohols including analogs that bear multiple functional groups.

Catalyst-Controlled, Site-Selective Sulfamoylation of Carbohydrate Derivatives

Methods for site-selective sulfamoylation of secondary hydroxyl groups in pyranosides are described. Using a boronic acid catalyst, selective installation of a Boc-protected sulfamoyl group at the equatorial position of cis-diols in manno- and galacto-configured substrates has been achieved. Activation of trans-diol groups in gluco- and galacto-configured substrates is also possible by employing an organotin catalyst.

Annulation Cascade of Sulfamate-Derived Cyclic Imines with Glycine Aldimino Esters: Synthesis of 1,3-Benzoxazepine Scaffolds

An efficient (3 + 2) cycloaddition triggered annulation is reported to access 1,3-benzoxazepine frameworks. With amine base, sulfamate-derived cyclic imines readily react with glycine aldimino esters to furnish benzo-fused seven-membered heterocyclic products in good yields. The cascade reaction involves the formation of one C-C, one C-N, and one C-O bond along with the cleavage of two C-N bonds and one S-O bond. The synthesis of o-tyrosine analogues has also been accomplished from annulation products.