73349-15-2Relevant academic research and scientific papers
An Atom-Economic and Stereospecific Access to Trisubstituted Olefins through Enyne Cross Metathesis Followed by 1,4-Hydrogenation
Ratsch, Friederike,Schmalz, Hans-Günther
supporting information, p. 785 - 792 (2018/01/27)
The combination of intermolecular enyne cross metathesis and subsequent 1,4-hydrogenation opens a stereocontrolled and atom-economic access to trisubstituted olefins. By investigating different combinations of functionalized alkyne and alkene substrates, we found that the outcome (yield, E / Z ratio) of the Grubbs II-catalyzed enyne cross-metathesis step depends on the substrate's structure, the amount of the alkene (used in excess), and the (optional) presence of ethylene. In any case, the 1,4-hydrogenation, catalyzed by 1,2-dimethoxybenzene-Cr(CO) 3, proceeds stereospecifically to yield exclusively the E -products from both the E- and Z- 1,3-diene intermediates obtained by metathesis. A rather broad scope and functional group compatibility of the method is demonstrated by means of 15 examples.
Gold-catalyzed isomerization of unactivated allenes into 1,3-dienes under ambient conditions
Ting, Chun-Ming,Hsu, Yi-Ling,Liu, Rai-Shung
, p. 6577 - 6579 (2012/07/31)
We have developed a gold-catalyzed isomerization of unactivated allenes into 1,3-dienes with nitrosobenzene as an additive. This reaction proceeded almost exclusively at room temperature for highly substituted allenes. The utility of this reaction is manifested by the development of one-pot [4+2]-cycloaddition of allenes and reactive alkenes.
The palladium-catalyzed addition of organoboronic acids to alkynes
Oh, Chang Ho,Jung, Hyung Hoon,Kim, Ki Seong,Kim, Nakjoong
, p. 805 - 808 (2007/10/03)
No base is necessary: Excellent yields are produced on addition of organoboronic acids to alkynes under mild reaction conditions when palladium compounds are used as catalysts (see scheme). Unlike the Suzuki-type cross-coupling reaction, the current reaction occurs in an acidic medium.
Palladium-catalyzed cyclization of ω-haloallenes. A new general route to common, medium, and large ring compounds via cyclic carbopalladation
Ma, Shengming,Negishi, Ei-Ichi
, p. 6345 - 6354 (2007/10/02)
A series of ω-haloallenes (4-32) as well as related ω-haloalkenes (41-45) were prepared through the application of known procedures. Their cyclization in the presence of a catalytic amount of Cl2Pd(PPh3)2, a base, e.g., K2CO3, and other appropriate reagents was investigated mostly under two sets of conditions (conditions I and II). The results summarized in Table 1 reveal the following: (1) The Pd-catalyzed cyclization reaction of ω-haloallenes gives the desired five- through twelve-membered and twenty-membered ring products in respectable yields. (2) The use of the dilute solution technique and n-Bu4NCl is advantageous in the synthesis of eight-membered and larger rings. (3) Formation of a carbon-carbon bond uniformly takes place at the central carbon of an allene. (4) The corresponding reaction of ω-haloalkenes fails to give eight- and nine-membered rings and displays an intriguing endo - exo cyclization mode vs ring size profile. (5) The eight-membered ring products were exclusively Z, and the eleven-, twelve-, and twenty-membered ring products were E. The stereochemistry of the nine- and ten-membered rings depends on other factors as well. The putative allylpalladium intermediates can be trapped with external nucleophiles, such as malonate esters, organostannanes, phenols, and amines, to give the corresponding derivatives. The results support the oxidative addition - carbopalladation mechanism leading to the formation of allylpalladium intermediates. The results also indicate that the extents of the actual cyclization process itself may be considerably higher than indicated by the yields of the dehydropalladation products and that some undesirable side reactions, such as double bond isomerization, can be circumvented through trapping with nucleophiles.
REGIOSELECTIVE ALKYLATION OF 3-SUBSTITUTED 3-SULFOLENES
Takayama, Hiroaki,Suzuki, Hiromasa,Nomoto, Takashi,Yamada, Sachiko
, p. 303 - 306 (2007/10/02)
Remarkable directing effect of the substituent on the double bond of 3-sulfolene was found in the reaction with alkyl iodides under basic conditions; electron donating groups effect selective substitution at the 2-position while electron withdrawing group
Novel and Convenient Method for the Stereo- and Regiospecific Synthesis of Conjugated Alkadienes and Alkenynes via the Palladium-Catalyzed Cross-Coupling Reaction of 1-Alkenylboranes with Bromoalkenes and Bromoalkynes
Miyaura, Norio,Yamada, Kinji,Suginome, Hiroshi,Suzuki, Akira
, p. 972 - 980 (2007/10/02)
Details of a new and general method for the stereo- and regiospecific synthesis of conjugated alkadienes and alkenynes are described.The reaction of (E)- or (Z)-1-alkenyldisiamylboranes, or 2-((E)-1-alkenyl)-1,3,2-benzodioxaboroles readily obtainable by hydroboration, with either (E)- or (Z)-1-alkenyl bromides in the presence of a catalytic amount of tetrakis(triphenylphosphine)palladium and bases such as sodium alkoxides gives the corresponding (E,E)-, (E,Z)-, (Z,E)-,or (Z,Z)-conjugated alkadienes stereo- and regiospecifically, while retaining the configurations of both the strating alkenylboranes and bromoalkenes.The reaction of (E)- and (Z)-1-alkenyldisiamylboranes with 1-bromoalkynes similarly provides a stereo- and regiospecific synthesis of conjugated (E)- and (Z)-alkenynes.A mechanism of this cross-coupling reaction, which involves the transmetalation between a 1-alkenylborane and an alkoxypalladium(II) complex generated through the metathetical displacement of a halogen atom from R(Pd(II)X with sodium alkoxide, is proposed.
Synthesis of Isomerically Pure (E)- and (Z)-1,3-Disubstituted 1,3-Dienes
Mulzer, Johann,Bruentrup, Gisela,Kuehl, Uwe,Hartz, Georg
, p. 3453 - 3469 (2007/10/02)
The (E)-dienes 1a - p were prepared in >98percent purity by dehydrative decarboxylation of the corresponding 4,5-unsaturated 3-hydroxycarboxylic acids 3 with dimethylformamide dimethylacetal (11).The (Z)-isomers 6a - m were obtained by stereouncontrolled
A STEREOSPECIFIC SYNTHESIS OF CONJUGATED (E,Z)- AND (Z,Z)-ALKADIENES BY A PALLADIUM-CATALYZED CROSS-COUPLING REACTION OF 1-ALKENYLBORANES WITH 1-ALKENYL BROMIDES
Miyaura, Norio,Suginome, Hiroshi,Suzuki, Akira
, p. 127 - 130 (2007/10/02)
The reactions of (Z)-1-alkenyldisiamylboranes with (Z)- or (E)-1-alkenyl bromides in the presence of a catalytic amount of tetrakis(triphenylphosphine)palladium and sodium ethoxide gave the corresponding conjugated (Z,Z)- or (Z,E)-alkadiene with high ster
