Bridged Polycyclic Compounds. V. The Addition of p-Thiocresol to Norbornadiene. The Question of Non-classical Free Radicals<sup>1,2</sup>

Cristol, Stanley J.; Brindell, Gordon D.; Reeder, James A.

doi:10.1021/ja01536a034

Cited by 46 publications

(13 citation statements)

References 3 publications

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“…Radical additions to norbornadiene 12 and its derivatives, using thiols for example, have been well-studied and usually result in substituted nortricyclanes as the major products. 16 Consistent with these earlier studies, we found that addition of p-thiocresol to norbornadiene 12 at 25 ЊC led to a mixture of nortricyclyl sulfide 14 and bicyclic sulfide 13 17,18 (Scheme 5, Table 1).…”

Section: Resultssupporting

confidence: 84%

Development of two processes for the synthesis of bridged azabicyclic systems: intermolecular radical addition–homoallylic rearrangements leading to 2-azanorborn-5-enes and neophyl-type radical rearrangements to 2-azabenzonorbornanes

2003

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Section: Resultssupporting

confidence: 84%

Development of two processes for the synthesis of bridged azabicyclic systems: intermolecular radical addition–homoallylic rearrangements leading to 2-azanorborn-5-enes and neophyl-type radical rearrangements to 2-azabenzonorbornanes

2003

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“…The structure assignment rests, besides analytical and spectral (ir, LIV) data, on the nmr spectra. All of the pyrazolines isolated had the exo attachment as co~n~nonly found in radical (8), ionic (9), and cycloaddition reactions (10) in bicyclo[2.2.1]heptene systems and also in 1,3-dipolar cycloadditions with diazoalkylphosphonates (2). This was shown' by the clear absence of coupling between the bridgehead hydrogens 4,7 and the hydrogens 5,6,9, and 10 (-90" angle, see ref.…”

Section: Do~tble P~ruzolines Jiom Ditnet/~~~lmentioning

confidence: 99%

1,3-Dipolar cycloadditions with diazomethylphosphonates. Double pyrazolines derived from norbornadiene

Cohen¹,

Benezra²

1976

Can. J. Chem.

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HUGUETTE COHEN and CLAUDE BENEZRA. Can. J. Chem. 54, 44 (1976). Four new exo-double pyrazolines 3-5 have been prepared from norbornadiene and diniethyl phenyldiazornethylpl~osphonate; their str~~ctures have been proven by nnir spectroscopy. There is a strong predominance of the isomers with the two aryl groiIps S J I I to the bridge. When the two aryl groups were different no electronic interaction between them could be detected by uv spectroscopy. Direct photolysis of the double pyrazolines leads to the corresponding d o~~b l e cyclopropanes with retention of configuration.HUGUETTE COHEN et CLAUDE BENEZRA. Can. J. Chem. 54, 44 (1976).Quatre nouvelles doubles pyrazolines e.uo 3-5 ont CtC prCparCes B partir du norbornadikne et du p11CnyldiazornCthylpl~osphonate de dimkthyle; leur structure est dCduite des spectres de rmn. I1 y a une forte predominance des isomkres dans lesquels les deux noyaux aryles sont S~I I par rapport au pont. Quand les deux groupes aryles sont diffirents il n'a Ct C detect6 aucune interaction Clectronique entre les noyaux aromatiques par spectroscopie uv. La photolyse directe des doubles pyrazolines conduit aux doubles cyclopropanes correspondants, avec retention de configuration.Norbornadiene provides a good model for studying 1,3-dipolar cycloadditions (1) with dimethyl aryl-and alkyldiazomethylphosphoilates RC(N2)P(0)(OMe)2 (2). The adducts (A1-pyrazolines) have a defined geoinetry which can be deduced mostly from nmr spectra making use of the reported vicinal 31P-C-C-lH couplings (3) and of stereospecific honzoa/lylic SJr.ir couplings (4). The stereoche~nical results with R = alkyl are in agreement with Huisgen's theory for a concerted nlechanis~n (2, 5) since steric factors are mainly responsible for the anti:sylz2 ratio of pyrazolines 1 and 2, but other effects seem to operate when an uryl (R = Aryl) diazo compound is being used (2). Usually the reaction was carried out with a large excess of

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“…Substituted cyclopropylmethyl–homoallylic radical systems are found embedded in a range of more complex substrates, such as those based upon the bicyclo[2.2.1]heptenyl (norbornenyl) framework. In these latter systems, nortricyclyl radical 3 can undergo reversible ring-opening to norbornenyl radical 4 ; treatment of nortricyclyl or norbornenyl bromide with Bu 3 SnH and AIBN is known to lead to the same (approximately equal) mixture of nortricyclane and norbornene [ 12 – 13 ]. The final product distribution in these systems is found to be heavily dependent on the reactant concentrations as well as on the structure of the substrate.…”

Section: Introductionmentioning

confidence: 99%

Radical cascades using enantioenriched 7-azabenzonorbornenes and their applications in synthesis

Hodgson¹,

Winning²

2008

Beilstein J. Org. Chem.

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Tandem deoxygenation-neophyl-type radical rearrangement-electrophile trapping using xanthates from 7-azabenzonorbornadienes gives 3-exo-substituted 2-aza-5,6-benzonorbornenes, which in some cases undergo isomerisation to (aminomethyl)indenes. The starting xanthates are accessible in good yields and high enantiomeric ratios via asymmetric hydroboration of (aryne/pyrrolederived) 7-azabenzonorbornadienes. Oxidation (using RuO 4 ) and Birch reduction of the 2-aza-5,6-benzonorbornenes provide access to substituted pyrrolidines and tetrahydroindenes, respectively.

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Bridged Polycyclic Compounds. V. The Addition of p-Thiocresol to Norbornadiene. The Question of Non-classical Free Radicals^1,2

Cited by 46 publications

References 3 publications

Development of two processes for the synthesis of bridged azabicyclic systems: intermolecular radical addition–homoallylic rearrangements leading to 2-azanorborn-5-enes and neophyl-type radical rearrangements to 2-azabenzonorbornanes

Development of two processes for the synthesis of bridged azabicyclic systems: intermolecular radical addition–homoallylic rearrangements leading to 2-azanorborn-5-enes and neophyl-type radical rearrangements to 2-azabenzonorbornanes

1,3-Dipolar cycloadditions with diazomethylphosphonates. Double pyrazolines derived from norbornadiene

Radical cascades using enantioenriched 7-azabenzonorbornenes and their applications in synthesis

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Bridged Polycyclic Compounds. V. The Addition of p-Thiocresol to Norbornadiene. The Question of Non-classical Free Radicals1,2

Cited by 46 publications

References 3 publications

Development of two processes for the synthesis of bridged azabicyclic systems: intermolecular radical addition–homoallylic rearrangements leading to 2-azanorborn-5-enes and neophyl-type radical rearrangements to 2-azabenzonorbornanes

Development of two processes for the synthesis of bridged azabicyclic systems: intermolecular radical addition–homoallylic rearrangements leading to 2-azanorborn-5-enes and neophyl-type radical rearrangements to 2-azabenzonorbornanes

1,3-Dipolar cycloadditions with diazomethylphosphonates. Double pyrazolines derived from norbornadiene

Radical cascades using enantioenriched 7-azabenzonorbornenes and their applications in synthesis

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Bridged Polycyclic Compounds. V. The Addition of p-Thiocresol to Norbornadiene. The Question of Non-classical Free Radicals^1,2