Sulfones a-bromo

Other direct methods for the sulfonation of the higher fatty acids are by the use of sulfur trioxide vapor or by the use of chlorosulfonic acid. Indirect methods are also available for the preparation of a-sulfo fatty acids and their salts from an a-bromo fatty acid made by the Hell-Volhard-Zelinsky reaction. The bromo compound may be converted directly to the sodium salt of a sulfonic acid through the Strecker reaction or may be converted to the mercaptan and oxidized to the sulfonate. Sulfonation of the lower fatty acids has been studied by Backer and co-workers. ... 

Pyridone IV was converted to its sodium salt by treatment with an equimolar amount of sodium methoxide in methanol (see procedure below under formation of the 3-phenyl-2(lH)pyridone sulfonates). The sodium salt was next treated with the methyl ester of a-bromo-p-toluic acid, obtained by treatment of the acid with BF3 etherate. 

A variety of cleavage conditions have been reported for the release of amines from a solid support. Triazene linker 52 prepared from Merrifield resin in three steps was used for the solid-phase synthesis of aliphatic amines (Scheme 22) [61]. The triazenes were stable to basic conditions and the amino products were released in high yields upon treatment with mild acids. Alternatively, base labile linker 53 synthesized from a-bromo-p-toluic acid in two steps was used to anchor amino functions (Scheme 23) [62]. Cleavage was accomplished by oxidation of the thioether to the sulfone with m-chloroperbenzoic acid followed by 13-elimination with a 10% solution of NH4OH in 2,2,2-trifluoroethanol. A linker based on l-(4,4 -dimethyl-2,6-dioxocyclohexylidene)ethyl (Dde) primary amine protecting group was developed for attaching amino functions (Scheme 24) [65]. Linker 54 was stable to both acidic and basic conditions and the final products were cleaved from the resin by treatment with hydrazine or transamination with ra-propylamine. 

The reaction of a-bromo or a-iodonitroalkanes with sodium benzenesulfinate gives a-nitro sulfones in 85-95% yields (Eq. 5.73), which proceeds via SRN1 reaction (Section 5.4).117... 

Feuer and co-workers also nitrated ring-substituted toluenes to the corresponding arylnitromethanes with potassium amide in liquid ammonia. Sulfonate esters and NJ -dialkylamides undergo similar nitration the latter isolated as their a-bromo derivatives. Alkaline nitration of ethyl and ferf-butyl carboxylic esters with potassium amide in liquid ammonia yields both the a-nitroester and the corresponding nitroalkane from decarboxylation. ... 

The Curtius rearrangement provides a route to carbamates of a-amino sulfonamides (Scheme 25). 108 Reaction of the ethyl ester of an a-bromo acid 52 with Na2S03 yielded the sodium salt of the corresponding sulfonic acid 53. Treatment of 53 with PQ5 afforded the sulfonyl chloride 54 which on reaction with an amine gave the sulfonamide 55. The latter... 

Table 3. Reaction of a-Bromo Vinyl Sulfone 77 with Heteroatom Nucleophiles...

A novel tandem process has been reported " for the preparation of allylic amines, ethers, and sulfides from a-bromo-a, jS-unsaturated sulfones. The process is believed to proceed via an initial conjugate addition followed by proton exchange and Ramberg-Backlund rearrangement (see Scheme 75). A new variant of the Ramberg-Backlund reaction has been described in which a, /f-epoxy sulfones (319), on treatment with base, are converted into a range of mono-, di-, and tri-substituted allylic alcohols (320). 

Since Werner s pioneering work on optical activity in complex inorganic compounds there have been many important developments in the field. One of the more interesting of these is known as the Pfeiffer effect which is a change in the optical rotation of a solution of an optically active substance e,g, ammonium d-a-bromo-camphor-T-sulfonate) upon the addition of solutions of racemic mixtures of certain coordination compounds (e,g, D,L-[Zn o-phen)z](NOz)2, where o-phen = ortho-phenan-throline). Not all combinations of complexes, optically active environments and solvents show the effect, however, and this work attempts to apply optical rotatory dispersion techniques to the problem, as well as to determine whether solvents other than water may be used without quenching the effect. Further, the question of whether systems containing metal ions, ligands, and optically active environments other than those already used will show the effect has been studied also,... 

Treatment of the epoxy sulfones obtained thus with MgBr2 produces a-bromo ketones or a-bromo al-dehyde. This conversion can be applied to stereoselective preparations of a-bromo methyl ketones from cyclohexanone derivatives. Thus, treatment of 17-P-hydroxy-5-a-androstan-3-one (134) with 1-chloroethyl phenyl sulfone provides an epoxy sulfone (135), which is cleaved by MgBr2 to give a 99 1 mixture of 3-acetyl-3-bromoandrostanes (136 and 137 equation 33), whereas similar treatment of 17-p-hydroxy-5-B-androstan-3-one (138) gives a 4 96 mixture of 3-acetyl-3-bromoandrostanes (139 and 140 equation 34). These facts may reflect the steric course of the initial attack of the a-sulfonyl carbanion on the carbonyl face. 

Retusamine, G19H25NO7 (mp 174.5° [ajp +13°), isolated by Gul-venor and Smith (77), was shown by Wunderlich (64) from X-ray diffraction of a single crystal of its a-bromo-( + )-camphor-frans-7r-sulfonate monohydrate to have structure GLX. The free base, however, is best... 

Spath and Leithe (225) reinvestigated the resolution of tetrahydroberberrubine with a-bromo-d-camphor-TT-sulfonic acid and from the first fraction obtained a base having [a] d +52°. This when fractionally crystallized from a variety of solvents ultimately yielded the d-base (m.p. 195-196°) of [a] +303° (chloroform) and [q ]b +298° (ethanol). The Z-base was similarly obtained from the first fractionation and had [aJi —304° (chloroform). These results were taken to indicate that Kitasato s conclusions Avere in error. 

---