624-75-9Relevant articles and documents
Methyl Radical Initiated Kharasch and Related Reactions
Tappin, Nicholas D. C.,Renaud, Philippe
supporting information, p. 275 - 282 (2020/12/07)
An improved procedure to run halogen atom and related chalcogen group transfer radical additions is reported. The procedure relies on the thermal decomposition of di-tert-butylhyponitrite (DTBHN), a safer alternative to the explosive diacetyl peroxide, to produce highly reactive methyl radicals that can initiate the chain process. This mode of initiation generates byproducts that are either gaseous (N2) or volatile (acetone and methyl halide) thereby facilitating greatly product purification by either flash column chromatography or distillation. In addition, remarkably simple and mild reaction conditions (refluxing EtOAc during 30 minutes under normal atmosphere) and a low excess of the radical precursor reagent (2 equivalents) make this protocol particularly attractive for preparative synthetic applications. This initiation procedure has been demonstrated with a broad scope since it works efficiently to add a range of electrophilic radicals generated from iodides, bromides, selenides and xanthates over a range of unactivated terminal alkenes. A diverse set of radical trap substrates exemplifies a broad functional group tolerance. Finally, di-tert-butyl peroxyoxalate (DTBPO) is also demonstrated as alternative source of tert-butoxyl radicals to initiate these reactions under identical conditions which gives gaseous by-products (CO2). (Figure presented.).
Cyanoacetic Acid as a Masked Electrophile: Transition-Metal-Free Cyanomethylation of Amines and Carboxylic Acids
Wang, Hongxiang,Shao, Ying,Zheng, Hao,Wang, Hanghang,Cheng, Jiang,Wan, Xiaobing
supporting information, p. 18333 - 18337 (2015/12/24)
Using cyanoacetic acid as a masked electrophile, a new cyanomethylation reaction of amines and carboxylic acids was developed, producing a variety of α-aminonitriles and cyanomethyl esters with good yields and excellent functionality tolerance. This protocol features simple manipulation, inexpensive reagents, and a wide substrate scope. Iodoacetonitrile was generated in situ from the iodination-decarboxylation of cyanoacetic acid in this transformation.
ANTHARQUINONE COMPOUNDS AS ANTI CANCER COMPOUNDS
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Page/Page column 15, (2008/06/13)
Anthraquinone compounds of the general formula (I) or a salt thereof (Formula I) in which R1 to R4 are each selected from the group consisting of H, C1-4 alkyl, X1, -NHR0N (R5)2 in which R0 is a C1-12 alkanediyl and each R5 is H or optionally substituted C1-4 alkyl, and a group of formula (II) in which at least one of R6,R7 and R8 is selected from X2 , and X2 substituted C1-4 alkyl and any others are H or C1-4 alkyl; R9 is selected from H, C1-4 alkyl, X2 and X2 substituted C1-4 alkyl; m is 0 or 1; n is 1 or 2; X1 is a halogen atom, a hydroxyl group, a C1-6 alkoxyl group, an aryloxy group or an acyloxy group; and X2 is a halogen atom, a hydroxyl group, a C1-6 alkoxyl group, an aryloxy group or an acyloxy group; provided that at least one of R1 to R4 is a group of formula (II). The N-oxides are useful prodrugs which are selectively bioreduced in hypoxic tumours to the corresponding cyclic amine derivatives. The amine compounds are cytotoxic and may be used as alkylating agents having topoisomerase II inhibiting activities in cancer therapy.
The Photolyses of 2,6- and 2,4-Difluorohalobenzenes
Song, Yong-Qi,Yuzuri, Tomoaki,Suezawa, Hiroko,Sakakibara, Kazuhisa,Hirota, Minoru,Nakada, Masahiro
, p. 1875 - 1878 (2007/10/03)
Photolyses of 2,6- and 2,4-difluorobromobenzenes in acetonitrile gave isomerized and brominated products in addition to 1,3-difluorobenzene produced by the dehalogenation.The reactions were compared with similar reactions of the corresponding chloro- and iodoarenes.In general, photolytic cleavage of the C-X bond of 2,6-difluorohalo(X)benzene was shown to proceed more easily than the corresponding 2,4-difluorohalo compound.
THE MECHANISM FOR NUCLEOPHILIC SUBSTITUTION OF α-CARBONYL DERIVATIVES. APPLICATION OF THE VALENCE-BOND CONFIGURATION MIXING MODEL.
McLennan, Duncan J.,Pross, Addy
, p. 981 - 984 (2007/10/02)
The valence-bond configuration mixing model (VBCM) is applied to the nucleophilic substitution reactions of α-carbonyl derivatives.The model appears to resolve satisfactorily a number of features of these reactions that current mechanisms have not dealt with.These include: (i) the dependence of the rate-enchancing effect of the carbonyl upon the nucleophilic strenght of the entering group, (ii) the unusually large Hammett ? value for the reaction of PhCOCH2Br with substituted pyridines, and (iii) the mechanism by which the rate-enhancing effect of the carbonyl group is transmitted to the reaction centre.
Carbon-Halogen Bonding Studies. Halogen Redistribution Reactions between Alkyl or Acetyl Halides and Tri-n-butyltin Halides
Friedrich, Edwin C.,Abma, Charles B.
, p. 1367 - 1371 (2007/10/02)
The equilibrium positions have been determined for the halogen redistribution reactions of tri-n-butyltin halides with a variety of structurally different types of alkyl halides and with acetyl halides.These have been related through the reaction ΔGo values to carbon-halogen bond dissociation energy differences.It is suggested that the trends observed in the latter may provide evidence for the existence of a small steric bond weakening effect in the order C-I > C-Br > C-Cl bonds on going from methyl to primary, secondary, and tertiary alkyl halides.On the other hand, with the 2,3-? bond containing allyl, benzyl, and propargyl halides , α-haloacetones, and haloacetonitriles, there may be some type of electronic carbon-halogen bond strengthening effect which lies in order C-I > C-Br > C-Cl.Finally, for the acetyl halides, the data are in agreement with increases in bond strengths resulting from ? contributions being in the order C-Cl > C-Br > C-I.
