2161-90-2Relevant articles and documents
Hetero-diels-alder reaction of ethyl 2-nitrosoacrylate and cyclohexadienes, and bromine induced diene isomerization
Song, Jian,Lin, Yongcheng,Szeto, Yau Shan,Chan, Wing Lai
, p. 1685 - 1689 (2007/10/03)
Bicyclic 8a-methoxy-1,2-oxazine (3a) and bicyclic 7-methoxy-1,2-oxazine (3b) were prepared via Hetero-Diels-Alder reaction between 1-methoxy-1,4-cyclohexadiene (2a) and ethyl 2-nitrosoacrylate generated in situ from ethyl bromopyruvate oxime (1). The formation of 3b was ascribed to bromine, released from 1, which induced transformation of 2a to 1-methoxy-1,3-cyclohexadiene (2b). 3b could be easily transformed to oxazinone (3c) in CHCl3, or other organic solvents in the presence of a trace amount of acid.{A figure is presented}.
Reductions with lithium in low molecular weight amines and ethylenediamine
Garst,Dolby,Esfandiari,Fedoruk,Chamberlain,Avey
, p. 7098 - 7104 (2007/10/03)
Reductions of several types of compounds with lithium and ethylenediamine using low molecular weight amines as solvent are described. In all cases 1 mol of ethylenediamine or N,N'-dimethylethylenediamine per gram-atom of lithium was used. In some cases it was beneficial to add an alcohol as a proton donor. These reaction conditions were applied to the debenzylation of N-benzylamide and lactams which are refractory to hydrogenolysis with hydrogen and a catalyst. N-Benzylpilolactam 2, synthesized from pilocarpine hydrochloride in refluxing benzylamine, was debenzylated in good yield using 10 gram-atoms of lithium per mole (10 Li/mol) of 2 in n-propylamine. The debenzylation of N-benzyl-N-methyldecanoic acid amide, 4 (6 Li/mol), in t-butylamine/N,N'-dimethylethylenediamine gave N-methyldecanoic acid amide 6 in 70% yield. Alternatively, reduction of 4 (7 Li/mol) in t-butanol/n-propylamine/ethylenediamine gave n-decanal 12 in 36% yield. Using the same conditions, thioanisole, 1-adamantane-p-toluenesulfonamide, and 1-adamantane methyl p-toluenesulfonate were reduced with 3, 7, and 7.2 Li/mol of compound to give thiophenol (74%), adamantamine (91%), and 1-adamantane methanol (75%), respectively. In this solvent system naphthalene and 3-methyl-2-cyclohexene-1-one were reduced to isotetralin (74%) and 3-methyl cyclohexanone (quantitative) with 5 and 2.2 Li/mol of starting compound, respectively. Oximes and O-methyloximes were reduced to their corresponding amines using 5 and 8 Li/mol of compound, respectively. Anisole was also reduced to 1-methoxy-1,4-cyclohexadiene with 2.5 Li/mol of anisole. Undecanenitrile was reduced to undecylamine with 8.6 Li/mol. Additionally, a base-catalyzed formation of imidazolines from a nitrile and ethylenediamine was also explored.
Two New Syntheses of the Pyranojuglone Pigment α-Caryopterone
Matsumoto, Takeshi,Ichihara, Akitami,Yanagiya, Mitsutoshi,Yuzawa, Tamio,Sannai, Akiyoshi,et al.
, p. 2324 - 2331 (2007/10/02)
By a simple process, 3-methoxyjuglone ( = 8-hydroxy-2-methoxy-1,4-naphthoquinone; 9) has been synthesized from 1,2,4-trimethoxybenzene (5) and converted, after prenylation, to α-caryopterone (1; Scheme 1), a pyranojuglone pigment from Caryopteris clandonensis.On the other hand, juglone ( = 5-hydroxy-1,4-naphthoquinone; 12) was regioselectively prenylated at C(2) via its 1-methoxy-cyclohexa-1,3-diene adduct 15 (Scheme 2).The 2-prenyljuglone (4) thus formed led to 1 after oxidation and other reactions.