81447-53-2Relevant academic research and scientific papers
New General Synthesis of tert-Butyl 3-Amino-2-naphthalenecarboxylates by an Electrocyclic Reaction of o-Quinonedimethides generated from tert-Butyl (Z)-3-Amino-3-(bicycloocta-1,3,5-trien-7-yl)prop-2-enoates
Kobayashi, Kazuhiro,Kanno, Yoshikazu,Seko, Shinzo,Suginome, Hiroshi
, p. 780 - 781 (2007/10/02)
A new general synthesis of tert-butyl 3-amino-2-naphthalenecarboxylates by an electrocyclic reaction of o-quinonedimethides thermally generated from tert-butyl (Z)-3-amino-3-(bicycloocta-1,3,5-trien-7-yl)prop-2-enoates is described.
Photoinduced Molecular Transformations. Part 135. New Synthesis of Taiwanin C and Justicidin E based on a Radical Cascade Process involving β-Scission of Alkoxy Radicals generated from 3- and 8-Aryl-1-ethyl-1,2-dihydrocyclobutanaphthalen-1-ols prepared by Thermolysis of (Z)-tert-...
Kobayashi, Kazuhiro,Kanno, Yoshikazu,Seko, Shinzo,Suginome, Hiroshi
, p. 3111 - 3118 (2007/10/02)
A new general synthesis of naturally occuring phthalide lignans, based on a radical cascade process triggered by a regioselective β-scission of the alkoxy radicals generated by photolysis of the hypoiodites of 8-aryl-1-ethyl-1,2-dihydrocyclobutanaphthalen-1-ols, is described.Two phases are involved in the present synthesis of phthalide lignans; the first is a new general synthesis of tert-butyl 4-aryl-3- and 4-aryl-8-aminonaphthalene-2-carboxylates by an electrocyclic reaction of o-quinonedimethides thermally generated from (Z)-tert-butyl 3-amino-3-(bicycloocta-1,3,5-trien-7-yl)propenoates; the second is a transformation of the protected 4-aryl-3-aminonaphthalene-2-carboxylic acids into the phthalide lignans.This latter phase involves their successive conversions into 3- and 8-arylcyclobutanaphthalen-1(2H)-ones via the formation of a benzyne intermediate, and then into 3- and 8-aryl-1-ethyl-1,2-dihydrocyclobutanaphthalen-1-ols, followed by β-scission of the alkoxy radicals generated by photolysis of their hypoiodites, generated in situ with the mercury(II) oxide-iodine reagent in benzene.Simultaneous syntheses of the naturally occuring phthalide lignans taiwanin C and justicidin E were thus achieved.
α,α-Dimethoxy-o-xylylene (5-(Dimethoxymethylene)-6-methylene-1,3-cyclohexadiene): Formation by 1,4-Elimination and Electrocyclic Routes and Reactions
Moss, Randall J.,White, Russell O.,Rickborn, Bruce
, p. 5132 - 5139 (2007/10/02)
The title reactive intermediate 4, which features an unprecedented (Z)-alkoxy substituent, is generated in two independent ways.The ortho ester 5 undergoes 1,4-elimination on treatment with lithium diisopropylamide, at convenient rates in the temperature range 50-70 deg C.In the absence of added dienophile, 4 generated in this manner forms a spiro dimer and a dimer, both involving bonding between the two unsubstituted methylene groups.Diels-Alder adducts of 4 with norbornene (NB), norbornadiene, and cyclopentene are described.The ketal 8 formed from 4 and NB undergoes further 1,4-elimination, generating a new o-xylylene which in turn adds a second NB to yield the novel bis-adduct 11.Thermal opening of α,α-dimethoxybenzocyclobutene (6) is also used to generate 4.Rate constants for this reaction were determined over the temperature range 132-168 deg C, through the use of N-phenylmaleimide, which efficiently traps the intermediate, thereby preventing reclosure to 6 and other decomposition reactions.The Ea for this electrocyclic opening is 33.6 kcal/mol; comparative data from the literature are discussed.In the absence of a dienophile, 4 generated in this way recloses to 6 as its major reaction pathway but also undergoes an unusual rearrangement to form methyl o-ethylbenzoate (26).The overall rate of this reaction is ca. one-tenth that of the opening of 6 to 4 and restricts the range of dienophiles which can be used to trap 4 generated from 6.For example, even at the lowest temperature (132 deg C) needed to observe electrocyclic opening, and in the presence of a very large excess of NB, competitive cycloadduct formation and rearrangement to 26 are observed.Flash vacuum pyrolysis of 6 was also briefly examined.
