(Bio)isosteres of ortho- and meta-substituted benzenes

• H. Erik Diepers and
• Johannes C. L. Walker

Beilstein J. Org. Chem. 2024, 20, 859–890, doi:10.3762/bjoc.20.78

• , deiodination at the bridgehead position, and nucleophilic substitution at the alkyl chloride. From 1,2-BCP (±)-4, a variety of 1,2-BCPs were prepared through basic chemical transformations (Scheme 1B) [26]. Selective deprotection gave access to free alcohol-containing 1,2-BCPs (±)-5 and (±)-8. Oxidation and

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

• 10. The selectivity for the non-dehydrogenated coumarins 10d is not understood, but 10b likely does not undergo dehydrogenation because there is no formation of aromaticity to drive the reaction forward. When the bicyclic alkene is substituted unsymmetrically at the bridgehead position, the reaction

All-carbon [3 + 2] cycloaddition in natural product synthesis

• Zhuo Wang and
• Junyang Liu

Beilstein J. Org. Chem. 2020, 16, 3015–3031, doi:10.3762/bjoc.16.251

• ] and [3.4.0] bicyclic systems bearing two quaternary atoms at the bridgehead position [49]. For instance, enynol 110 was treated with 5 mol % of [RhCl(CO)2]2 and carbon monoxide to afford a [3.3.0] bicycle 111 in 87% yield (Scheme 8A). The proposed catalytic cycle of this elegant rhodium-catalyzed

Formation of an exceptionally stable ketene during phototransformations of bicyclo[2.2.2]oct-5-en-2-ones having mixed chromophores

• Asitanga Ghosh

Beilstein J. Org. Chem. 2020, 16, 2297–2303, doi:10.3762/bjoc.16.190

• like phenyl or isopropenyl at the bridgehead position were analyzed for the first time in different solvents and upon irradiation with different wavelengths. In all cases, a regioselective photoinduced 1,5-phenyl migration leading to vinyl ketenes from the more congested site of the molecule to the

• carried out the photoreactions of 5,6-dibenzoyl-4-phenylbicyclo[2.2.2]oct-5-en-2-one (7a) and 5,6-dibenzoyl-4-isopropenylbicyclo-[2.2.2]oct-5-en-2-one (7b) in detail (Figure 2). Both of the molecules contain electron-acceptor groups like phenyl and isopropenyl at its bridgehead position (C-4) and these

• been reported from our laboratory for bicyclo[2.2.2]octenone systems [13]. Thus, selective formation of 10a,b is expected with the exception that the ketenes 10a,b were unusually stable. This may be due to the imposition of the bulky electron-withdrawing group at the bridgehead position. The non

Towards triptycene functionalization and triptycene-linked porphyrin arrays

• Gemma M. Locke,
• Keith J. Flanagan and
• Mathias O. Senge

Beilstein J. Org. Chem. 2020, 16, 763–777, doi:10.3762/bjoc.16.70

• -substituted triptycene structures such as 9-iodotriptycene. However, this design is limited as with larger functional groups at the bridgehead position impose alternate packing patterns [45]. The structure of the porphyrin–triptycene–porphyrin dimer 16 (Figure 3) was solved with one molecule in the asymmetric

Palladium-catalyzed ring-opening reactions of cyclopropanated 7-oxabenzonorbornadiene with alcohols

• Katrina Tait,
• Oday Alrifai,
• Rebecca Boutin,
• Jamie Haner and
• William Tam

Beilstein J. Org. Chem. 2016, 12, 2189–2196, doi:10.3762/bjoc.12.209

• the nucleophile at bridgehead carbon A, resulting in cleavage of the C–O bond. Through deprotonation at the bridgehead position and an internal rearrangement, 2-methyldihydronaphthalen-1-ols 9 could be formed. This type 1 ring opening has been accomplished by our group through the use of organocuprate

Bridgehead vicinal diallylation of norbornene derivatives and extension to propellane derivatives via ring-closing metathesis

• Sambasivarao Kotha and
• Rama Gunta

Beilstein J. Org. Chem. 2016, 12, 1877–1883, doi:10.3762/bjoc.12.177

• values [41]. Conclusion This methodology was found to be useful to synthesize various propellane derivatives containing a norbornene moiety by employing RCM sequence. Moreover, we have firmly established the configuration of allyl groups at bridgehead position of norbornene derivatives by single-crystal

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

• oxidative fragmentation at the bridgehead position of adamantanes 157a,b. The reaction employed the trifluoroperacetic acid (TFPAA)/trifluoroacetic acid (TFAA) system and afforded compounds 158a,b in high yields (Scheme 46) [300]. This method for the insertion of an oxygen atom was applied to the oxidation

Mitomycins syntheses: a recent update

• Jean-Christophe Andrez

Beilstein J. Org. Chem. 2009, 5, No. 33, doi:10.3762/bjoc.5.33

• both this methoxy group and the one at the ring junction. Finally, the nitrogen of the lactam is located in the bridgehead position of a [3.3.0] bicycle resulting in poor delocalization into the adjacent carbonyl. A Barton deoxygenation gave compound 43, which was irradiated to decompose the triazoline

Analogues of amphibian alkaloids: total synthesis of (5R,8S,8aS)-(−)-8-methyl- 5-pentyloctahydroindolizine (8-epi-indolizidine 209B) and [(1S,4R,9aS)-(−)-4-pentyloctahydro- 2H-quinolizin- 1-yl]methanol

• Joseph P. Michael,
• Claudia Accone,
• Charles B. de Koning and
• Christiaan W. van der Westhuyzen

Beilstein J. Org. Chem. 2008, 4, No. 5, doi:10.1186/1860-5397-4-5

• through bicyclic enaminone intermediates in which the alkene bond is located between the bridgehead position and the adjacent site, we have a convenient and dependable method for introducing the correct relative stereochemistry at these two sites by means of catalytic hydrogenation. However, the

• ]. Finally, since the pendent substituents in the indolizidine series can be induced to adopt a trans-orientation by base-catalysed epimerisation of a carbonyl substituent adjacent to the bridgehead position (cf Scheme 1), it should in principle be possible to effect a similar epimerisation in the