17615-02-0Relevant articles and documents
Palladium-Catalyzed Long-Range Deconjugative Isomerization of Highly Substituted α,β-Unsaturated Carbonyl Compounds
Lin, Luqing,Romano, Ciro,Mazet, Clément
supporting information, p. 10344 - 10350 (2016/08/31)
The long-range deconjugative isomerization of a broad range of α,β-unsaturated amides, esters, and ketones by an in situ generated palladium hydride catalyst is described. This redox-economical process is triggered by a hydrometalation event and is thermodynamically driven by the refunctionalization of a primary or a secondary alcohol into an aldehyde or a ketone. Di-, tri-, and tetrasubstituted carbon-carbon double bonds react with similar efficiency; the system is tolerant toward a variety of functional groups, and olefin migration can be sustained over 30 carbon atoms. The refunctionalized products are usually isolated in good to excellent yield. Mechanistic investigations are in support of a chain-walking process consisting of repeated migratory insertions and β-H eliminations. The bidirectionality of the isomerization reaction was established by isotopic labeling experiments using a substrate with a double bond isolated from both terminal functions. The palladium hydride was also found to be directly involved in the product-forming tautomerization step. The ambiphilic character of the in situ generated [Pd-H] was demonstrated using isomeric trisubstituted α,β-unsaturated esters. Finally, the high levels of enantioselectivity obtained in the isomerization of a small set of α-substituted α,β-unsaturated ketones augur well for the successful development of an enantioselective version of this unconventional isomerization.
New access to trisubstitutea 3-pyrrolines under phosphine catalysis
Schuler, Marie,Duvvuru, Deepti,Retailleau, Pascal,Betzer, Jean-Francois,Marinetti, Angela
supporting information; scheme or table, p. 4406 - 4409 (2009/12/26)
Conjugated dienes, properly activated by electron-withdrawing groups on both ends, are shown to be suitable substrates for phosphinepromoted organocatalytic processes. Their reactions with imines, under phosphine catalysis, afford a new and efficient synthetic approach to functionalized 3-pyrrolines.
Flash Vacuum Pyrolysis of Stabilised Phosphorus Ylides. Part 1. Preparation of Aliphatic and Therminal Alkynes
Aitken, R. Alan,Atherton, J. Ian
, p. 1281 - 1284 (2007/10/02)
Thermal extrusion of Ph3PO from β-oxoalkylidenetriphenylphosphoranes 4 to give the alkynes 5, which under conventional pyrolysis conditions is restricted to cases in which R1 is an electron withdrawing group, has been successfully achieved for R1=H or alkyl by using FVP.The method allows convenient construction of multigram quantities of the alkynes 5 from alkyl halides 1 and allows convenient construction of multigram quantities of the alkynes 5 from alkyl halides 1 and acid chlorides 3 in three steps with good overall yields.Under the conditions used the ylides with R2 = cyclobutyl also undergo less of ethene to provide convenient access to the vinylalkynes 6.
Prostanoids and related compounds. V. Synthesis of 6-aza-5-oxo-2,3,4-trinor-1,5-inter-m-phenylene prostacyclin derivatives
Miyajima,Takemoto,Achiwa
, p. 3175 - 3179 (2007/10/02)
6-Aza-5-oxo-2,3,4-trinor-1,5-inter-m-phenylene prostacyclin derivatives were synthesized by use of 1,3-dipolar cycloaddition as a key step.
Novel vitamin D analogues
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, (2008/06/13)
This invention relates to vitamin D analogues represented by the general formula I STR1 in which formula X stands for hydrogen, lower alkyl, halogen or hydroxy; Y stands for hydrogen or hydroxy; R1 and R2, which may be the same or different, stand for lower alkyl, optionally substituted with halogen or hydroxy with the proviso that R1 and R2 cannot both be methyl when X is other than lower alkyl, or, taken together with the carbon atom numbered 25, R1 and R2 can form a saturated or unsaturated C3 -C9 carbocyclic ring which may optionally be substituted at any possible position(s) with lower alkyl, halogen or hydroxy; R3 stands for hydrogen or lower alkyl; R4 and R5 represent either each hydrogen, or when taken together constitute a bond, with the result that a double bond connects carbon atoms numbered 22 and 23; and bioreversible derivatives thereof. The compounds of the invention have a favorable therapeutic index and are particularly useful in the treatment of human and veterinary disorders which are characterized by abnormal cell proliferation and/or cell differentiation.
