Hydrogenations of cycloalkenes using tris(triphenylphosphine)chlororhodium(I)

Hussey, Allen S.; Takeuchi, Y.

doi:10.1021/ja01031a026

Cited by 59 publications

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“…We then turned our attention to the diphosphines 7 and 8 which would form a seven-membered ring of chelation with a rhodium atom. We may draw attention to the important difference between the diphosphine 7 and its open-chain analog 8, namely, the greater rigidity of 7, due to the transconfiguration of the dioxolan ring patents pending.…”

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confidence: 99%

Asymmetric catalytic reduction with transition metal complexes. I. Catalytic system of rhodium(I) with (-)-2,3-0-isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)butane, a new chiral diphosphine

Kagan¹,

1972

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The catalytic system (-)-(diop)-Rh(I) (diop = 2,3-0-isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)butane (7)) is described and is used for an extensive study of the hydrogenation of various precursors of alanine, phenylalanine, tyrosine, Dopa, and leucine. Optical yields in the range of 70-80 % are obtained in the reduction of ^-substituted -acetamidoacrylic acids. The presence of a carboxyl group is found not to be absolutely necessary for good optical yield. The favorable effect of the enamide function on the catalytic process is deduced from comparisons of the rates of hydrogenation of atropic and acetamidocinnamic acids, from the optical yields obtained in the reduction of different precursors of phenylalanine, and from the high optical yield (78 %) obtained in the hydrogenation of the enamide 12, a compound having no carboxyl groups.

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confidence: 99%

Asymmetric catalytic reduction with transition metal complexes. I. Catalytic system of rhodium(I) with (-)-2,3-0-isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)butane, a new chiral diphosphine

Kagan¹,

1972

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“…Furthermore, the stereochemistry of the addition of D, by this method is known to be cis. 4 The single deuterium atom at the CH, OH…”

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confidence: 99%

Chemical shifts in methylcyclohexane

Lambert

Takeuchi

1969

Org. Magn. Reson.

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In order to determine the effect of a single methyl group on the chemical shifts of protons in a cyclohexane ring, methylcyclohexane-1 ,2,3,3,5,5-d6 has been synthesized. The protons in the 4-position and the 2,6-equatorial protons are not significantly different from those in ring-frozen cyclohexane. The 2,6-axial protons, however, experience an up-field shift of about 15 Hz from the position of the other axial protons. These observations are discussed in terms of the structure of me thy lcyclohexane .

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“…We then move forward to the challenging chemoselective Δ 7,14 reduction of 15 and 15a precursors; thus, initially 15 was subjected to hydrogenation using various catalysts (Pd/C, Pd(OH) 2 /C, and Pt/C) and solvent systems, which resulted in a complex mixture due to nonselective reaction pathways. To our surprise, Wilkinson’s reduction of 15 and 15a using RhCl(PPh 3 ) 3 and H 2 (50 psi) in benzene at 70 °C showed great selectivity but delivered undesired stereoisomeric products 7- epi -beshanzuenone D ( 16 ) and 7,9-di- epi -beshanzuenone D ( 16a ) in 82 and 80% yield, respectively. This stereochemical outcome could be due to the steric influenced convex facial (α-face) attack of the hydrogenation catalytic system onto the 15 or 15a (Scheme ).…”

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Total Synthesis of Beshanzuenone D and Its Epimers and Abiespiroside A

2020

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A unified and protecting-group-free six-step total synthesis of bisabolane-type sesquiterpenoid beshanzuenone D and its stereoisomers and abiespiroside A using S-(+)-carvone as a common chiral-pool building block is disclosed. This synthetic route features chemoselective allylic chlorination of carvone, Au(I)-catalyzed cycloisomerization induced construction of furan from homopropargylic diol, substrate-controlled selective hydroxylation using Davis-oxaziridine, and dye-sensitized photo-oxidation (through 1O2) of hydroxyalkyl tethered furan to access oxaspirolactone as key transformations. A comprehensive set of NMR data along with DFT calculations, ECD spectra, and optical rotation measurements of the synthesized beshanzuenone D and its epimers were obtained to confirm absolute configurations.

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Hydrogenations of cycloalkenes using tris(triphenylphosphine)chlororhodium(I)

Cited by 59 publications

References 0 publications

Asymmetric catalytic reduction with transition metal complexes. I. Catalytic system of rhodium(I) with (-)-2,3-0-isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)butane, a new chiral diphosphine

Asymmetric catalytic reduction with transition metal complexes. I. Catalytic system of rhodium(I) with (-)-2,3-0-isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)butane, a new chiral diphosphine

Chemical shifts in methylcyclohexane

Total Synthesis of Beshanzuenone D and Its Epimers and Abiespiroside A

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