94223-45-7Relevant academic research and scientific papers
Unlocking the 5-exo Pathway with the AuI-Catalyzed Alkoxycyclization of 1,3-Dien-5-ynes
Virumbrales, Cintia,Suárez-Pantiga, Samuel,Marín-Luna, Marta,Silva López, Carlos,Sanz, Roberto
, p. 8443 - 8451 (2020/07/04)
The first general regio- and stereoselective 5-exo gold(I)-catalyzed alkoxycyclization of a specific class of 1,5-enynes such as 1,3-dien-5-ynes has been described, despite 1,5-enynes being known to almost invariably proceed via endo cyclizations under gold-catalysis. The configuration of the terminal alkene in the starting 1,3-dien-5-yne plays a crucial role on the regiochemical outcome of the reaction. A wide variety of interesting alkoxy-functionalized alkylidenecyclopentenes have been synthesized from 1-monosubstituted (E)-1,3-dien-5-ynes. On the contrary, the corresponding Z isomers evolve affording formal 6-endo cyclization products. In addition, mechanistic exploration supports a highly stabilized carbocation as a key intermediate instead of a highly constrained cyclopropyl gold carbene from E isomers, and also accounts for the well differentiated reactivity observed between both E/Z geometrical isomers as well as for the stereochemical outcome of the reaction.
Palladium-Catalyzed Cross-Coupling of β-(Methanesulfonyl)oxy Enones with Organostannanes
Hettrick, Christina M.,Kling, James K.,Scott, William J.
, p. 1489 - 1492 (2007/10/02)
β-(Methanesulfonyl)oxy enones, derived from 1,3-diones, cross-couple with vinylstannanes in 50-80percent yields when a substoichiometric amount of Pd(PPh3)4 and stoichiometric lithium bromide are used.Phenyltributylstannane affords low yields of cross-coupled product.Tetrabutyltin, tributyltin hydride, and ethynyltributyltin do not couple under the reaction conditions.The reaction is proposed to involve in situ formation of the β-bromo enone, oxidative addition to the Pd(0) catalyst, transmetalation, and reductive elimination to afford cross-coupled products.The analogous enol phosphates undergo coupling in low yields, the major product resulting from regeneration of the 1,3-dione.
A STUDY OF PERISELECTIVITY IN THE THERMAL CYCLISATION REACTIONS OF DIENE-CONJUGATED DIAZO COMPOUNDS: 1,7-CYCLISATION AS A ROUTE TO 3H-1,2-DIAZEPINES AND 1,5-CYCLISATION LEADING TO NEW REARRANGEMENT REACTIONS OF 3H-PYRAZOLES
Robertson, Ian R.,Sharp, John T.
, p. 3095 - 3112 (2007/10/02)
A range of diene-conjugated diazo compounds has been generated by the thermal decomposition of the sodium salts of the tosylhydrazones of 1-acyl-1,3-dienes. Those of type (21) with a cis relationship of the diazo group and the γ,δ-double bond and having a cis hydrogen atom at the dien terminus cyclised only by 1,7 ring closure to give 3H-1,2-diazepines (23).This mode of cyclisation was inhibited by the presence of cis methyl or phenyl groups at the diene terminus eg in (45). Compounds of this type cyclised by the alternative 1,5- ring closure to give 3-alkenyl-3H-pyrazoles eg (46) as primary products. These observations are explained on the basis of a helical transition state (54) for the 8? electron 1,7-electrocyclisation reaction. Diene-conjugated diazo compounds with a trans γ,δ double bond eg (32) also cyclised predominantly by 1,5-electrocyclisation to give 3-alkenyl-3H-pyrazoles eg (33). In most cases the 3H-pyrazoles rearranged under the reaction conditions via alkenyl group and hydrogen migrations to give 1H-pyrazoles eg (34) and (37).
