Phenyl sulfone derivative hydrogenation

Pedersen and coworkers investigated the El mass spectra of several 2-hydroxyphenyl alkyl sulfones (39) and sulfoxides (Section II.B). The methyl derivative seemed to fragment only via sulfinate ester formation giving the primary product ions m/z 157 and 109 (equation 14). Obviously hydrogen bonding between the ortho hydroxyl and the sulfone sulfur makes the loss of CH3SO2 difficult in contrast to the situation in methyl phenyl sulfone. The sulfinate ester rearrangement is not important when R>Et in 39. 

Hydrogenation of fluoromethyl-acetylene derivative of methyl phenyl sulfone Pd/CaCOj Florfenicol MASR... 

In a further exanple. Smith and Wan exploited the nucleophilic capability of l-phenyl-2-tetrazoline-5-thione in the Mitsunobu reaction, followed by oxidation to the sulfone with hydrogen peroxide and ammonium heptamolybdate tetrahydrate as a key step in a synthesis of the ansamycin antiobiotic, (+ )-thiazinotrienomycin-E (eq 8). Importantly, use of the phenyltetrazolylthione-derived sulfone gave an 13Z ratio of 10 1 in this coupling whereas the more conventional benzthiazole-2-thiol-derived system resulted in a selectivity of only 1.5 1 in favor of the -isomer. 

M. Shi and Y.-L. Shi reported the synthesis and application of new bifunctional axially chiral (thio) urea-phosphine organocatalysts in the asymmetric aza-Morita-Baylis-Hillman (MBH) reaction [176, 177] of N-sulfonated imines with methyl vinyl ketone (MVK), phenyl vinyl ketone (PVK), ethyl vinyl ketone (EVK) or acrolein [316]. The design of the catalyst structure is based on axially chiral BINOL-derived phosphines [317, 318] that have already been successfully utilized as bifunctional catalysts in asymmetric aza-MBH reactions. The formal replacement of the hydrogen-bonding phenol group with a (thio)urea functionality led to catalysts 166-168 (Figure 6.51). 

The preparation of chelating surface-active diphosphines proved to be more successful. The BDPP analogue R,R-(9) was synthesized by lithiation of tris[p-(3-phe-nylpropyl)phenyl]phosphine, reaction with (R,R)-2,4-pentane-diylditosylate and subsequent sulfonation with concentrated sulfuric acid [16]. Hydrogenation of the prochiral olefin (Z)-2-(N-acetamido)cinnamic acid ester in a two-phase system (ET0Ac/H20) with Rh complexes derived from R,R-(9) was accomplished with identical selectivity compared with the unsulfonated BDPP and improved reactivity compared with BDPPTS (2). 

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