Chemistry of Fenchonesulfonic Acid Derivatives

Abstract

(1 S) - (+)-Fenchone is sulfonated by SO3 or H2SO4/acetic anhydride in the bridgehead methyl group. This could be confirmed by NMR techniques (INADEQUATE). The fenchonesulfonic acid obtained is converted (SOCl2/NH3) to the cyclic fenchonesulfonimide, which can be oxidized to the corresponding oxaziridine, in close analogy to 10-camphorsulfonimide. Improved procedures for this reaction sequences are given. During the treatment of the sulfonic acid with thionyl chloride, a byproduct with a rearranged bicyclic skeleton is observed whose structure has been determined by ozonolytic degradation and NMR techniques. A possible mechanism for this rearrangement is suggested, based on MNDO calculations of the intermediate carbocations. The fenchonesulfonyloxaziridine oxidizes sulfides to chiral sulfoxides with appreciable enantiomeric excess, but very low reaction rate. A comparison with camphor-derived oxaziridines having similar steric requirements is made.

Synthesis and Reactions of exo-Camphorylsulfonyloxaziridine

“…An important advantage of the camphorylsulfonyloxaziridines is that on oxidation of the corresponding imines they are obtained as single isomers because the exo face of the C−N double bond is blocked by the methyl group of the methylene bridge. In all of the diverse types of camphorylsulfonyloxaziridines prepared to date, only single isomers are produced which have the endo structure exclusively, e.g., 1 and 2 . − , Thus the fact that the X-ray structure of (+)- 4a indicated that it had the exo structure rather than the endo structure 3 was quite unexpected (Figure ). This must mean that fusion of the 6-membered ring to camphor results in a ring conformation of 9 such that endo attack by the peracid oxidizing reagent is much less favorable than exo attack.…”

Coupling agents with 2,4,6,8-tetramethylcyclotetrasiloxane core – synthesis and application in styrene–butadiene rubber production

“…12 These compounds are characterized by flexibility, high strength of Si-O bonds, and high reactivity under specified conditions in miscellaneous organic reactions, i.e., hydrolysis, 13 halogenation, 14 dehydrogenative couplings, 15,16 silylative coupling, 17,18 alkylative cleavage, 19 Piers-Rubinsztajn reaction, 20 ring-opening polymerizations, 21,22 and hydrosilylation. [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] 8-Membered compounds such as DH 4 , because of the possible modification of peripheral Si-H groups by a hydrosilylation reaction, have opened access to several functional materials. While cyclosiloxanes have been utilized as substrates in the synthesis of dendritic molecules, 40 films 41,42 and coatings, 30,43 sensors, 44,45 liquid crystallines, 46,47 electrolytes, 48 ceramics, 49 and membranes, 50 there are no reports of their use as precursors of silica modifiers or coupling agents.…”

“…The addition reactions of DH 4 to various olefins have been the subject of numerous reports. The most widely described group of products is DR 4 derivatives, which have four identical groups pendent from the cyclosiloxane core and are obtained by hydrosilylation between DH 4 and unsaturated compounds, including non-functional aliphatic olefins, 38,51 perfluoroalkenes, 23 cycloalkenes, 32 alkenylbenzenes, 24,27,39 allyl alcohol derivatives, 28,34 allylamines, 35,37 alkenyl acid esters, 31,33 vinylsilanes, 25,29,36 and alkynes. 26 Hydrosilylation reactions focused on the modification of DH 4 with two different substrates (olefin or alkyne) leading to products with different content of the groups DSP 3 , DS 2 P 2 or DS 3 P are a more challenging task, definitely less frequently described in the scientific journals, and mainly disclosed in the patent literature.…”