19785-01-4Relevant articles and documents
Cobalt-Catalyzed Allylic C(sp3)-H Carboxylation with CO2
Michigami, Kenichi,Mita, Tsuyoshi,Sato, Yoshihiro
supporting information, p. 6094 - 6097 (2017/05/08)
Catalytic carboxylation of the allylic C(sp3)-H bond of terminal alkenes with CO2 was developed with the aid of a Co/Xantphos complex. A wide range of allylarenes and 1,4-dienes were successfully transformed into the linear styrylacetic acid and hexa-3,5-dienoic acid derivatives in moderate to high yields, with excellent regioselectivity. The carboxylation showed remarkable functional group tolerability, so that selective addition to CO2 occurred in the presence of other carbonyl groups such as amide, ester, and ketone. Since styrylacetic acid derivatives can be readily converted into optically active γ-butyrolactones through Sharpless asymmetric dihydroxylation, this allylic C(sp3)-H carboxylation showcases a facile synthesis of γ-butyrolactones from simple allylarenes via short steps.
Oxocarbons and related compounds. 27. Synthesis of dihydrocyclobuta[a]naphthalene-1,2-diones and cyclobuta[a]naphthalene-1,2-diones via annulation of alkoxy-(1-alkenyl)benzenes with 3-chloro-3-cyclobutene-1,2-dione. Scope and limitations
Schmidt, Arthur H.,Kircher, Gunnar,Spring, Mathias,Hendriok, Markus W.,Kuenz, Christian
, p. 564 - 574 (2007/10/03)
The reaction of alkoxy-(1-alkenyl)benzenes with semisquaric chloride (3) has been investigated systematically. 1,2-Dialkoxy- and 1-alkoxy′-2-alkoxy″-4-(1-alkenyl)benzenes (6a-j) and (11a-i) react with 3 to give the 3,4-dihydrocyclobuta[a]naphthalene-1,2-diones(8a-j) and (12a-i). Treatment of the dihydrocyclobuta[a]naphthalene-1,2-diones with 1.2 equiv. bromine effects dehydrogenation and affords cyclobuta[a]naphthalene-1,2-diones(9a-e) and (13b-f). Any efforts to extend this annulation reaction to dimethoxy-(1-alkenyl)benzenes with the methoxy groups in other than the 1,2-positions, e. g. 14a, b, 16a, b have been unsuccessful. The reaction of 1,2,3-trimethoxy-4-(1-propenyl) [and 4-(1-butenyl)]-benzenes (18a) and (18b) with semisquaric chloride (3) leads to the elimination of HCl and CH3OH and gives 5,6-dimethoxy-3-methyl [and 3-ethyl]-cyclobuta[a]naphthalene-1,2-diones (20a) and (20b). The reaction pathway of this novel annulation reaction is discussed.
High pressure nucleophilic fluoride-ion substitution reactions: Formation of fluoroalkylbenzenes
Gerdes, John M.,Keil, Robert N.,Shulgin, Alexander T.,Mathis, Chester A.
, p. 121 - 129 (2007/10/03)
A series of 1-phenyl-2-tosyloxy- and 1-phenyl-3-tosyloxyalkanes was synthesized and then subjected to tetrabutylammonium fluoride in THF under 15 kbar (1.5 GPa), 8 kbar or 1 bar pressures. The resultant substitution and elimination reaction product distributions were analyzed. The application of pressure enhanced the progress of the fluoride-ion substitution reactions. The degree of selectivity of the one reaction over the other was found to be a function of tosylate substrate structure and the amount of pressure applied. The exclusive formation of fluoroalkanes from 1-phenyl-2-tosyloxyalkane substrates under 15 kbar pressure demonstrated the potential of the pressure method for prospective use in fluorine-18 radiolabelling applications.
