Medium-sized cyclophanes, part 59:1 Nitration of [3.3]- and [3.3.3]metacyclophanes — Through-space electronic interactions between two or three benzene rings

2002 ◽  
Vol 80 (2) ◽  
pp. 207-215 ◽  
Author(s):  
Takehiko Yamato ◽  
Koji Tsuchihashi ◽  
Noriko Nakamura ◽  
Mai Hirahara ◽  
Hirohisa Tsuzuki
Keyword(s):  
Acetic Anhydride ◽  
Electronic Interaction ◽  
Reaction Conditions ◽  
Tert Butyl ◽  
Mixed Acid ◽  
Butyl Group ◽  
Tert Butyl Group ◽  
Starting Compound ◽  
Nitration Product ◽  
Fuming Nitric Acid

The two tert-butyl groups of anti-6,15-di-tert-butyl-9,18-dimethoxy[3.3]metacyclophane (anti-4) are both ipso-nitrated even under mild reaction conditions such as copper(II) nitrate in an acetic anhydride solution because of the decreased deactivation of the second aromatic ring by the introduced nitro group. On the other hand, anti-5,13-di-tert-butyl-8,16-dimethoxy[2.2]metacyclophane (anti-1) undergoes replacement of only one tert-butyl group under the same reaction conditions. The higher yields of the twofold ipso-nitration product anti-7 were obtained in nitration of anti-4 with fuming nitric acid or mixed acid (HNO3–H2SO4). Thus, the number of ipso-nitrations at the tert-butyl groups of anti-4 was strongly affected by the reactivity of the nitration reagent. Nitration of the corresponding syn-conformer syn-4 with copper(II) nitrate in an acetic anhydride solution, however, led only to the recovery of the starting compound. The presently developed procedure was further applied to the direct removal of the tert-butyl group by electrophilic substitution of the larger-sized ring macrocyclic metacyclophanes, cone- and partial-cone-tri-tert-butyl[3.3.3]metacyclophanes 11.Key words: [3n]metacyclophanes, conformation, ipso-nitration, through-space electronic interaction, crystal structure.

Medium-sized cyclophanes. part 51. Acylation of [2.2]metaparacyclophanes: through-space electronic interactions between two benzene rings

2000 ◽  
Vol 78 (2) ◽  
pp. 238-247 ◽  
Author(s):  
Takehiko Yamato ◽  
Kiwamu Tokuhisa ◽  
Hirohisa Tsuzuki
Keyword(s):  
Benzene Ring ◽  
Acetyl Chloride ◽  
Electrophilic Aromatic Substitution ◽  
Electronic Interaction ◽  
Aromatic Substitution ◽  
Reaction Conditions ◽  
Tert Butyl ◽  
Butyl Group ◽  
Tert Butyl Group ◽  
Sigma Complex

The acylation of 8-methyl- (1b) and 8-methoxy[2.2]metaparacyclophane 1c with 1.1 equiv. of acetyl chloride in CS2 solution in the presence of aluminum chloride afforded 15-acetyl-8-methyl- (2b) and 12-acetyl-8-methoxy[2.2]metaparacyclophanes (3c) with 65 and 41% yields, respectively. The different orientations for the electrophilic substitution were observed to be dependant on the substituent at the 8 position. On the other hand, when the same reaction was carried out under the same reaction conditions with the corresponding 5-tert-butyl derivatives (11), ipso-acetylation at the tert-butyl group was observed along with acetylation on the para-benzene ring. The substituent effect on the 8-position was also observed in the present ipso-acetylation. The ipso-acylation at the tert-butyl group of 5-tert-butyl-8-methoxy[2.2]metaparacyclophane (11c) is attributed to the highly activated character of the aryl ring and the increased stabilization of a sigma-complex intermediate arising from the dienone-type sigma-complex intermediate possible in the case of a internal methoxy substituent. However, the present ipso-acetylation has not been observed in mild reaction conditions such as acetyl chloride in the presence of TiCl4 catalyst due to deactivation of the second aromatic ring by the introduced acetyl group on the para-benzene ring. The mechanism of these novel reactions is also discussed.Key words: cyclophanes, electrophilic aromatic substitution, regioselectivity, through-space electronic interaction, ipso-acylation.

ipso-Nitration of tert-butyl[n.2]metacyclophanes; through-space electronic interactions between two benzene rings

1998 ◽  
Vol 76 (7) ◽  
pp. 997-1005 ◽  
Author(s):  
Takehiko Yamato ◽  
Hideo Kamimura ◽  
Hirohisa Tsuzuki
Keyword(s):  
Electronic Interaction ◽  
Reaction Conditions ◽  
Electronic Interactions ◽  
Face To Face ◽  
Tert Butyl ◽  
Anti Conformer ◽  
Nitration Product ◽  
Group A ◽  
Fuming Nitric Acid ◽  
Methoxy Substituent

The selective introduction of one or two nitro groups by direct replacement of tert-butyl groups via the ipso aromatic nitration of the meta-bridged aromatic compounds having two arene rings is described. The ipso-nitration at the tert-butyl groups of syn- and anti-di-tert-butyl-dimethoxy[n.2]metacyclophanes 1 is attributed to the highly activated character of the aryl ring and the increased stabilization of a σ-complex intermediate arising from the dienone-type σ-complex intermediate possible in the case of an internally methoxy substituent. However, only one tert-butyl group is ipso-nitrated in the mild reaction conditions such as copper(II) nitrate in an acetic anhydride solution because of deactivation of the second aromatic ring by the introduced nitro group. A first σ-complex intermediate would be stabilized by two types of the through-space electronic interaction, i.e., face-to-face overlapping and intra-annular interaction with the opposing benzene ring, thus accelerating the reaction. The higher yields of mononitrated product are obtained in syn-conformer than in anti-conformer. Therefore, face-to-face overlapping might be much more favourable to stabilize the first σ-complex intermediate than the intra-annular interaction. On the other hand, nitration of 1 with fuming nitric acid afforded the two-fold ipso-nitration product 3 in quantitative yield. Thus, the number of ipso-nitration at the tert-butyl groups of 1 was strongly affected by the reactivity of the nitration reagent.Key words: cyclophanes, electrophilic aromatic substitutions, ipso-nitration, σ-complex intermediates, through-space electronic interactions.

ipso-Acylation of 5,13-di-tert-butyl-8,16-dimethyl[2.2]metacyclophane with acid anhydrides: Through-Space Electronic Interaction among the Two Benzene Rings

2009 ◽  
Vol 2009 (5) ◽  
pp. 298-301 ◽  
Author(s):  
Tomoe Shimizu ◽  
Arjun Paudel ◽  
Takehiko Yamato
Keyword(s):  
Aromatic Ring ◽  
Electronic Interaction ◽  
Tert Butyl ◽  
Butyl Group ◽  
Tert Butyl Group ◽  
Benzene Rings ◽  
Acid Anhydrides

Acylation of 5,13-di- tert-butyl-8,16-dimethyl[2.2]metacyclophane with acid anhydrides led to mono- ipso-acylation at the tert-butyl group to give 5-acyl-13- tert-butyl-8,16-dimethyl[2.2]metacyclophanes, from which the second electrophilic substitition with acid anhydrides can be strongly suppressed because of deactivation of the second aromatic ring by acyl group introduced by the through-space electronic interaction.

Medium-sized cyclophanes. Part 62:1 Formylation of anti-[n.2]metacyclophanes — Through-space electronic interactions between two benzene rings

2003 ◽  
Vol 81 (3) ◽  
pp. 244-252 ◽  
Author(s):  
Takehiko Yamato ◽  
Tsuyoshi Furukawa ◽  
Kan Tanaka ◽  
Tsutomu Ishi-i ◽  
Masashi Tashiro
Keyword(s):  
Methyl Ether ◽  
Electrophilic Aromatic Substitution ◽  
Similar Reaction ◽  
Reaction Conditions ◽  
Ring Inversion ◽  
Electronic Interactions ◽  
Strained Molecules ◽  
Tert Butyl ◽  
Butyl Group ◽  
Tert Butyl Group

Formylation of anti-[n.2]metacyclophanes (1) (n = 2, 3, 4) with dichloromethyl methyl ether in the presence of TiCl4 occurred selectively at para-position to the internal methyl substituents of anti-[n.2]metacyclophanes. Similar reaction of anti-5,13-di-tert-butyl-8,16-dimethyl[2.2]metacyclophane (6a) with dichloromethyl methyl ether in the presence of TiCl4 led to ipso-formylation at the tert-butyl group to give anti-5-tert-butyl-13-formyl-8,16-dimethyl[2.2]-meta cyclophane (7a) as well as the corresponding 2,7-di-tert-butyl-trans-10b,10c-dimethyl-10b,10c-dihydropyrene (10), anti-5-tert-butyl-8,16-dimethyl-13-(3-methyl-1-butene-2-yl)[2.2]metacyclophane (8), and anti-5,13-di-tert-butyl-exo-1-hydroxy-8,16-dimethyl[2.2]metacyclophane (9) depending on the reaction conditions. The higher yield of ipso-formylated product is obtained in the presence of AlCl3 MeNO2 in 80% yield along with anti-5-tert-butyl-8,16-dimethyl-13-(3-methyl-1-butene-2-yl)[2.2]metacyclophane (13). Thus, the yield of ipso-formylation at the tert-butyl group of 6a was strongly affected by the activity of the formylation catalyst. Interestingly, in the formylation of anti-6,14-di-tert-butyl-9,17-dimethyl[3.2]metacyclophane (6b) under the same reaction conditions, syn-6,14-di-tert-butyl-7-formyl-9,17-dimethyl[3.2]metacyclophane (14b) was obtained in 40% yield arising from the anti-syn-ring inversion of the formylation intermediate along with ipso-formylation product 7b in 42% yield. In the formylation of anti-[4.2] meta cyclophane (6c) only the mono-ipso-formylated product 7c was obtained in 92% yield. The formation of a two-fold ipso-formation product, i.e., anti-5,13-diformyl-8,16-dimethyl[2.2]metacyclophane (3a), was not observed under the reaction conditions used. The mechanism of the ipso-formation as well as the formation of the present novel reaction products 8 and 9 is also discussed. Key words: cyclophanes, strained molecules, electrophilic aromatic substitution, ipso-formylation, σ-complex intermediates, through-space electronic interactions.

Ipso nitration. XX. Nitration of 5-tert-butyl-1,2,3-trimethylbenzene in acetic anhydride. Formation and rearomatization of adducts

1978 ◽  
Vol 56 (13) ◽  
pp. 1758-1768 ◽  
Author(s):  
Alfred Fischer ◽  
Khay Chuan Teo
Keyword(s):  
Acetic Anhydride ◽  
Major Product ◽  
Aqueous Acetone ◽  
Main Reaction ◽  
Aqueous Acetic Acid ◽  
Aqueous Methanol ◽  
Tert Butyl ◽  
Butyl Group ◽  
Tert Butyl Group ◽  
Acidic Conditions

Nitration of 5-tert-butyl-1,2,3-trimethylbenzene in acetic anhydride gives both diastereomers of the adduct 1-tert-butyl-3,4,5-trimethyl-4-nitrocyclohexa-2,5-dienyl acetate and one diastereomer of 1-tert-buty]-3,4,5-trimethyl-4-nitrocyclohexa-2,5-dienol, in 91% yield, together with 5-tert-butyl-1,2,3-trimethyl-4-nitrobenzene. Solvolysis of the dienyl acetate in acidified aqueous acetone and acidified methanol affords the diastereomers of the dienols and the dienyl methyl ethers, respectively. The dienyl methyl ethers are also formed from the dienyl acetate in neutral methanol and again on reaction with methanolic sodium methoxide. The dienols isomerize (epimerize) in acidified aqueous acetone. Reaction of the dienyl methyl ethers in aqueous methanol, or prolonged reaction in methanol, results in the formation of methyl-1,2,3-trimethylphenyl ether. Similar cleavage of the tert-butyl group is the main reaction on solvolysis of the dienyl acetate in aqueous acetic acid. Under more acidic conditions the dienyl acetate gives 5-tert-butyl-2,3-dimethylbenzyl nitrite and lesser amounts of 5-tert-butyl-2,3-dimethylphenylnitromethane and 5-tert-butyl-2,3-dimethylbenzyl acetate. In trifluoromethanesulfonic and fluorosulfonic acids 5-tert-butyl-1,2,3-trimethyl-4-nitrobenzene is the major product.

Reactions of benzyl methyl substituted-benzyl phosphites with tert-butyl hypochlorite: "balanced TS" validating reactivity/selectivity principle

1998 ◽  
Vol 76 (6) ◽  
pp. 836-842
Author(s):  
Sung Soo Kim ◽  
Yu Zhu ◽  
In Seok Oh ◽  
Chang Gyeong Lim
Keyword(s):  
Benzyl Chloride ◽  
Activation Parameters ◽  
Differential Activation ◽  
Tert Butyl ◽  
Benzyl Chlorides ◽  
Butyl Group ◽  
Tert Butyl Group ◽  
Polar Transition ◽  
Isokinetic Relations ◽  
Selectivity Principle

Reactions of a series of several benzyl methyl substituted-benzyl phosphites with tert-butyl hypochlorite were investigated. The reactions produced phosphates, isobutene, alkyl chlorides, and benzyl chlorides via phosphonium chlorides as intermediates. Furthermore, the phosphates bearing a tert-butyl group underwent fragmentation to yield isobutene and another phosphates. Relative rates of formations of substituted benzyl and benzyl chloride (kY/kH) were measured at the temperatures (-20, 0, 20, 40°C). Logarithms of the rates (log kY/kH) were plotted against sigma + and 1/T, respectively. The former gave Hammett correlations to suggest a polar transition state (TS). The latter yielded differential activation parameters (ΔΔ Hdouble daggerY-H and ΔΔ Sdouble daggerY-H ), which indicate isokinetic relations and enthalpy control of rates. The selectivities (kY/kH) decrease with higher temperatures and thereby follow the reactivity/selectivity principle.Key words: phosphites, tert-butyl hypochlorite, Hammett correlations, differential activation terms, reactivity/selectivity principle.

Evaluation of the tert-butyl group as a probe for NMR studies of macromolecular complexes

2021 ◽  
Author(s):  
Rashmi Voleti ◽  
Sofia Bali ◽  
Jaime Guerrero ◽  
Jared Smothers ◽  
Charis Springhower ◽  
...  
Keyword(s):  
Nmr Studies ◽  
Macromolecular Complexes ◽  
Tert Butyl ◽  
Butyl Group ◽  
Tert Butyl Group

Michael addition of amines to sterically crowded ortho-benzoquinone completed with unprecedented 1,2-shift of a tert-butyl group

Tetrahedron ◽  
2021 ◽  
Vol 79 ◽  
pp. 131841
Author(s):  
Eugeny Ivakhnenko ◽  
Vasily Malay ◽  
Galina Romanenko ◽  
Oleg Demidov ◽  
Pavel Knyazev ◽  
...  
Keyword(s):  
Michael Addition ◽  
Tert Butyl ◽  
Butyl Group ◽  
Tert Butyl Group

Tri(Terf-Butyl)plumbyl-phosphanes, Synthesis and Multinuclear Magnetic Resonance

2000 ◽  
Vol 55 (10) ◽  
pp. 939-945 ◽  
Author(s):  
Max Herberhold ◽  
Christian Köhler ◽  
Volker Tröbs ◽  
Bernd Wrackmeyer
Keyword(s):  
Magnetic Resonance ◽  
Phosphorus Atom ◽  
Coupling Constants ◽  
Tert Butyl ◽  
Nmr Data ◽  
Butyl Group ◽  
Tert Butyl Group ◽  
Multinuclear Magnetic Resonance

AbstractThe reaction of tri(tert-butyl)plumbyl-lithium (1) with various phosphorus chlorides was studied. With diphenyl- and amino(phenyl)phosphorus chlorides the formation of hexa(tertbutyl) diplumbane (2) and tetraphenyldiphosphane (3) or the respective 1,2-bis(am ino)-1,2-diphenyl- diphosphanes [e. g. 5: amino = PhCH2(tBu)N] was dominant. The presence of at least one tert-butyl group at the phosphorus atom gave access to tri(tert-butyl)plumbyl-di(tert-butyl) phosphane (4) and to tri(tert-butyl)plumbyl-amino(tert-butyl)phosphanes [amino = tBu(H)N (6), Me(Ph)N (7), PhCH2(Me)N (8), PhCH2(tBu)N (9)] via the reaction of 1 with the corresponding phosphorus chlorides. Side products were again 2 and the corresponding diphosphanes, unidentified compounds, and in two cases, bis(phosphanyl)-di(tert-butyl)plumbanes [phosphanyl = tBu(H)N(tBu)P (10), Me(Ph)N(tBu)P (11)]. Trimethylplumbyl-benzyl(methyl)- amino(tert-butyl)phosphane (12) was prepared for comparison. All compounds were characterized by their 1H , 13C, 15N (9 ),31P and 207Pb NMR data. The coupling constants 1J(207Pb,31P) are large and negative, whereas the coupling constants 1J(207Pb, 13C) are small and can be of either sign. The coupling constants 2J(31P-N-13C) of 6 - 12 indicate a preferred conformation of the substituents at phosphorus and nitrogen

ChemInform Abstract: A CASE OF A FACILE CLEAVAGE OF AN ANGULAR TERT-BUTYL GROUP

1981 ◽  
Vol 12 (28) ◽  
Author(s):  
V. A. KAMINSKII ◽  
T. V. ZABOLOTNOVA ◽  
T. V. NOVIKOVA ◽  
T. M. TILICHENKO
Keyword(s):  
Tert Butyl ◽  
Butyl Group ◽  
Tert Butyl Group
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