61827-88-1Relevant articles and documents
Highly selective synthesis of conjugated dienoic and trienoic esters via alkyne elementometalation - Pd-catalyzed cross-coupling
Wang, Guangwei,Mohan, Swathi,Negishi, Ei-Ichi
, p. 11344 - 11349 (2011/10/30)
All four stereoisomers (7-10) of ethyl undeca-2,4-dienoate were prepared in ≥98% isomeric purity by Pd-catalyzed alkenylation (Negishi coupling) using ethyl (E)- and (Z)-β-bromoacrylates. Although the stereoisomeric purity of the 2Z,4E-isomer (8) prepared by Suzuki coupling using conventional alkoxide and carbonate bases was ≤95%, as reported earlier, the use of CsF or nBu4NF as a promoter base has now been found to give all of 7-10 in ≥98% selectivity. Other widely known methods reveal considerable limitations. Heck alkenylation was satisfactory for the syntheses of the 2E,4E and 2E,4Z isomers of ≥98% purity, but the purity of the 2Z,4E isomer was ≤95%. Mutually complementary Horner-Wadsworth-Emmons and Still-Gennari (SG) olefinations are also of considerably limited scopes. Neither 2E,4Z nor 2Z,4Z isomer is readily prepared in ≥90% selectivity. In addition to (2Z,4E)-dienoic esters, some (2Z,4E,6E)- and (2Z,4E,6Z)-trienoic esters have been prepared in ≥98% selectivity by a newly devised Pd-catalyzed alkenylation-SG olefination tandem process. As models for conjugated higher oligoenoic esters, all eight stereoisomers for ethyl trideca-2,4,6-trienoate (23-30) have been prepared in ≥98% overall selectivity.
Stereoselective syntheses of (E)- and (Z)-1-arylalk-3-en-1-ynes and (E,E)-, (Z,E)-, (E,Z)-, and (Z,Z)-alka-1,5-dien-3-ynes via a one-pot multicomponent coupling reaction
Hoshi, Masayuki,Nakayabu, Hidenori,Shirakawa, Kazuya
, p. 1991 - 2007 (2007/10/03)
Both 1-arylalk-3-en-1-ynes and alka-1,5-dien-3-ynes have been synthesized under extremely mild reaction conditions in good to high yields via a sequential Suzuki-type and Sonogashira reaction in a one-pot manner. Thus, the protocol involves Cu-mediated cross-coupling reaction of (E)- or (Z)- alkenyldisiamylborane with (trimethylsilyl)ethynyl bromide in the presence of 1M NaOMe and Pd/Cu-catalyzed cross-coupling reaction with aryl or alkenyl iodide in the presence of aqueous n-Bu4NOH. The reaction with aryl iodide is tolerant of a wide variety of functional groups on the aromatic ring and leads to the stereoselective formation of (E)- and (Z)-1-arylalk-3-en-1-ynes. In addition, the reactions with (E)- and (Z)-1-iodoalk-1-enes have accomplished the construction of all possible combinations of geometrical isomers, (E,E)-, (Z,E)-, (E,Z)-, and (Z,Z)-alka-1,5-dien-3-ynes. Georg Thieme Verlag Stuttgart.
Synthesis of allenic diols by samarium, diiodide-promoted coupling between alkynyloxiranes and ketones
Aurrecoechea, Jose M.,Alonso, Eva,Solay, Monica
, p. 3833 - 3850 (2007/10/03)
The SmI2-mediated reductive coupling between alkynyloxiranes and ketones provides a new route to 2,3-pentadiene-1,5-diols. The preferred stereochemistry observed in the coupling products is the result of the new C- C bond forming anti with respect to the opening epoxide ring. Yields and diastereoselectivities are dependent on the alkynyloxirane substitution pattern.
