Benzonorbornene and derivatives. II. ac-Bromobenzonorbornenes and -dienes

Wilt, James W.; Chenier, Philip J.

doi:10.1021/jo00830a065

Cited by 28 publications

(13 citation statements)

References 2 publications

(3 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…By path A, 2‐bromonorbornadiene 2b and 2,3‐dibromonorbornadiene 4b were prepared through a synthetic procedure modified from that originally reported by Szeimis 5. The first bromination step for norbornene, benzonorbornadiene, naphthonorbornadiene and 5,8‐(dimethoxy)benzonorbornadiene4 was more conveniently (Scheme ) performed under radical conditions, with 1,2‐dibromotetrachloroethane serving as the source of bromine in CCl 4 solution 6. Under these reaction conditions, the Wagner−Meerwein rearrangement of the polycyclic skeleton of the intermediate carbocation was totally suppressed,7 and compounds 1a and 1c − e were obtained predominantly as their anti ‐dibrominated isomers.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of 2-Mono- and 2,3-Disubstituted Polycyclic Alkenes

et al. 2002

View full text Add to dashboard Cite

show abstract

Section: Resultsmentioning

confidence: 99%

Synthesis of 2-Mono- and 2,3-Disubstituted Polycyclic Alkenes

et al. 2002

View full text Add to dashboard Cite

show abstract

“…Diels-Alder Cycloaddition of 1,3-Butadiene to Benzonorbornadiene-1-carboxylic Acid (8). The ester 7 was hydrolyzed by 5% aqueous sodium hydroxide to 8, which had the physical constants as reported.…”

Section: Methodsmentioning

confidence: 92%

“…The oil obtained was analyzed by VPC and the two products were isolated by preparative thin-layer chromatography using benzene solvent. The major and less polar product was identified as dibenzobicyclo[2.2.2]octadien-1-yl triflate (13): mp 93-94 "C; NMR (CDC13) 6 1.65-2.7 (m, 4 H, ethylene bridge), 4.25 (t, 1 H, bridgehead), 7.0-7.7 (m, 8 H, aromatic). Anal.…”

Section: Methodsmentioning

confidence: 99%

Acetolysis of dibenzonorbornadienyl-1-carbinyl trifluoromethanesulfonate and comparison with the norbornyl-1-carbinyl system and its unsaturated analogs

Irie¹,

Tanida²

1978

J. Org. Chem.

View full text Add to dashboard Cite

The preparation of dibenzonorbornadienyl-1-carbinyl derivatives (5) is described. The acetolysis of the trifluoromethanesulfonic acid ester (triflate, gives the acetate with retention of configuration and the internally returned dit~enzobicyclo[2.2.2]octadien-l-y1 triflate (13). The acetolysis of the benzonorbornadienyl-1-carbinyl system (4) previously reported is reinvestigated using the triflate and shown to proceed by a similar pathway. The acetolysis of dibenzobicyclo[2.2.2]octadienyl-l-carbinyl triflate (6-OTf) gives only the ring-enlarged dibenzobicyclo[3.2.2]nonadien-l-y1 acetate (14). These rates and products are compared with those reported in acetolyses of norbornyl-1-carbinyl (I), norbornenyl-1-carbinyl (2), and benzonorbornenyl-1-carbinyl (3) arenesulfonates. The absence of the unsaturated bridge-migrated products is established. The dissociation constants of the corresponding bridgehead acids are determined in 50% aqueous ethanol. A linear relation is found between the logarithms of the acetolysis rates and the dissociation constants. Therefore, evidence for anchimeric assistance by the unsaturated link,sge in these systems is not found; rather the inductive effect of these bonds accounts for the results observed.Solvolysis of bicyclic bridgehead neopentyl systems proceeds with ready rearrangements forming bridgehead substituted pr0ducts.l A representative example is the acetolysis of norbornyl-1-carbinyl tosylate (1-OTs) which produced bicyclo[2.2.2]octyl-l-yl acetate in 85% yield.2 Effects of unsaturation in the [2.2.1] system have been investigated by Wilt,Bly, and their co-workers with norbornenyl-1-carbinyl tosylate (2)374 and benzonorbornenyl-1-carbinyl tosylate (3).5 Of particular interest are the absence of etheno (or benzo) bridge-migrated products and the formation of considerable amounts of unrearranged products. Introduction of additional unsaturation has been investigated by Chenire e t a1.6 with benzonorbornadienJy1-1-carbinyl tosylate (4). A major path of this acetolysis proceeds without accompanying rearrangement. Interest in the changes of the rearrangement manner with unsaturation led us t o undertake a study of the dibenzonorbornadienyl-1-carbinyl system (5) and, in addition, the Scheme I CH2X A --C H~O T S I -OTS A3 OAc CH2X CH2X 2 3 CH2X 4 5 6 butadiene COOR 7 R = E t a R = H COOR COOMe 9 R = H 10 R = Me @& + @& -5-OTf (OTf-OS02CFd COOMe C H20H 12 5 -O H dibenzobicyclo[2.2.2]octadienyl-l-carbinyl system (6). With these present results the solvolytic behavior of bicyclo[2.2.1] bridgehead neopentyl systems will be complete.

show abstract

“…For that reason, we at first prepared the corresponding starting material, 2,3-dibromobenzonorbornadiene (26), by addition of bromine to 22 [24] at 77°C followed by dehydrobromination. However, the addition of bromine to the carbonϪcarbon double bond in 22 at room temperatures or lower resulted in the formation of rearranged tribromide 23 in quantitative yield as a result of WagnerϪMeerwein rearrangement (Scheme 5).…”

Section: Synthesis Of the Starting Materialsmentioning

confidence: 99%