Roversi, Elena published the artcileSubstituent effect on the competition between hetero-Diels-Alder and cheletropic additions of sulfur dioxide to 1-substituted 1,3-butadienes, Safety of Allyldiphenylphosphine oxide, the publication is Helvetica Chimica Acta (2002), 85(3), 733-740, database is CAplus.
The reactivity of sulfur dioxide toward variously substituted butadienes was explored in an effort to define the factors affecting the competition between the hetero-Diels-Alder and cheletropic additions At low temperature (<-70¡ã), 1-alkyl-substituted 1,3-dienes that can adopt s-cis-conformations add to SO2 in the hetero-Diels-Alder mode in the presence of CF3COOH as promoter. In the case of (E)-1-ethylidene-2-methylidenecyclohexane, the [4+2] cycloaddition of SO2 is fast at -90¡ã without acid catalyst. (E)-1-(Acyloxy)-1,3-butadienes also undergo the hetero-Diels-Alder addition with SO2+CF3COOH at low temperatures, giving a 1:10 mixture of the corresponding cis- and trans-6-(acyloxy)sultines. Above -50¡ã, the sultines undergo complete cycloreversion to the corresponding dienes and SO2, which that add in the cheletropic mode at higher temperature to give the corresponding 2-substituted sulfolenes. The hetero-Diels-Alder additions of SO2 follow the Alder endo rule, giving first the 6-substituted cis-sultines that equilibrate then with the more stable trans-isomers. This statement is based on the assumption that the S=O group in the sultine prefers a pseudo-axial rather than a pseudo-equatorial position, as predicted by quantum calculations The most striking observation is that electron-rich dienes , such as 1-cyclopropyl-1,3-butadiene, 1-phenyl-1,3-butadiene, 1-(4-methoxyphenyl)-1,3-butadiene, 1-(trimethylsilyl)-1,3-butadiene, 1-phenoxy-1,3-butadiene, 1-(4-chlorophenoxy)-1,3-butadiene, 1-(4-methoxyphenoxy)-1,3-butadiene, 1-(4-nitrophenoxy)-1,3-butadiene, 1-(2-naphthalenyloxy)-1,3-butadiene, 1-(methylthio)-1,3-butadiene, 1-(phenylthio)-1,3-butadiene, 1-[(4-chlorophenyl)thio]-1,3-butadiene, 1-[(4-methoxyphenyl)thio]-1,3-butadiene 1-[(4-nitrophenyl)thio]-1,3-butadiene, and 1-(phenyl-seleno)-1-1,3-butadiene, as well as 1-(methoxymethylene)-2-methylenecyclohexane do not equilibrate with the corresponding sultines between -100¡ã and -10¡ã in the presence of large excess of SO2, with or without acidic promotor. The hetero-Diels-Alder additions of SO2 to 1-substituted (E)-1,3-butadienes are highly regioselective, giving exclusively the corresponding 6-substituted sultines. The 1-substituted (Z)-1,3-butadienes do not undergo the hetero-Diels-Alder additions with sulfur dioxide.
Helvetica Chimica Acta published new progress about 4141-48-4. 4141-48-4 belongs to catalysis-chemistry, auxiliary class Aryl phosphine ligand,Mono-phosphine Ligands, name is Allyldiphenylphosphine oxide, and the molecular formula is C15H15OP, Safety of Allyldiphenylphosphine oxide.
Referemce:
https://courses.lumenlearning.com/boundless-chemistry/chapter/catalysis/,
Catalysis – Wikipedia