S -Me-PennPhos

Guy Solladie Frau9oise Colobert University Louis Pasteur, Strasbourg, France 

Handling, Storage, and Precautions PennPhos is air-sensitive storage of PennPhos and all operations that involve handling of PennPhos should be performed under an inert atmosphere. In general, aryldialkylphosphines are irritants skin contact should be avoided, and care should be exercised to avoid vapor inhalation. 

Alternate Name (7 ,5,7 ,5)-PP -l,2-phenylenebis(endo-2,5-dim-ethyl-7-phospha-bicyclo[2.2.1]heptane). 

Physical Data viscous oil [a]n +221.8°(c= 1.01, CHCI3). Solubility soluble in CHCI3 and other common organic solvents. Form Supplied in not commercially available. 

Preparative Methods it can be prepared from p-xylene and 1,2-phenylenediphosphorane in four synthetic steps (eq 1). 

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A Rh complex with (/f.S. /f.S -Me-PennPhos efficiently catalyzes asymmetric hydrogenation of simple ketones (Figure 1.22). Addition of catalytic amounts of 2,6-lutidine is crucial to achieve high enantioselectivity. This catalyst is also... 

Among the various Rh-phosphine catalysts used to perform enantioselective hydrogenation of lV-(3,4-dihydro-l-naphthyl)ac-etamide, Rh-(R,5,R,S)-Me-PennPhos afforded the desired hydrogenation product in highest optical yield. Thus, the use of Rh-L catalysts, where L = (S,5)-(-e)-DIOP (1), (R)-(-e)-BINAP (2), and (R,R)-(—)-Me-DuPhos (3), afforded lV-(l,2,3,4-tetrahydro-l-naphthyl)acetamide in only 10% ee(S), 24% ee (R), and 1% ee (R, with 57% conversion). ... 

Longer reaction times are required to achieve maximum conversion when aliphatic ketones are hydrogenated in the presence of Rh-(R,S,R,S)-Me-PennPhos catalyst. Thus, 2-hexanone is reduced by H2 [30 atm, Rh-(R,S,R,S)-Me-PennPhos catalyst in the presence of KBr (1 equiv)] at room temperature. After 48 h, the chemical yield of (S)-2-hexanol is 96% (optical yield 75% ee). ... 

Table 1 Asymmetric hydrogenations of prochiral alkenes catalyzed by a (/ ,S,/f,S)-Me-PennPhos-Rh(I) complex...

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