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Conformation Design of Open-Chain Compounds

“…For 2-chloro-and 2-bromo-4-methylpentane 25 (X Cl, Br), it had been shown earlier by IR studies [66] that conformer 25 a with the halogen atom lateral to the main chain predominates. An analysis of NMR coupling constants for a series of 2-heteroatom-substituted 4-methylpentanes 25 [67] showed that the conformational preferences are rather small (see Table 1). The largest effects were recorded for electronegative residues such as phthalimidyl-, chloro-, or bromo-substituents.…”

“…The tendency of electronegative heteroatoms to adopt a position lateral to the main hydrocarbon chain [70] has been exploited by Dirk Stenkamp in a systematic study [67,71] of 2,4-disubstituted pentanes (29, Table 2). The conformational preferences for the chloro-and bromo compounds, estimated from the vicinal 3 J H,H coupling constants, agree with previous reports.…”

Synthesis, Conformational Analysis, and Biological Activity of Proposed Vitronectin Antagonists

“…This substitution pattern was chosen based on the well-known importance of synpentane interactions in controlling conformation [61]. A series of studies by Hoffmann and coworkers have examined these principles in the context of acyclic conformational control.…”

“…(12a)). Different groups in the 2-and 4-positions influence the conformations formed by the hydrocarbon backbone in order to minimize unfavorable steric and electronic interactions [62]. This effect was evident in the conformations adopted by 2-hydroxy-4-vinylpentane, which was found to exist as an a:b ratio of 3.5:1 as a result of decreased gauche interactions between the vinyl group and the proton attached to the tertiary carbon adjacent to the hydroxyl group (Fig.…”

Synthesis and Biological Evaluation of Bromo‐ and Fluorodanicalipin A

“…[18] Removal of both TBS ethers then afforded diol 12, which was subjected to bromination with PhNMe 3 Br 3 to deliver the desired product with d.r. [18] Removal of both TBS ethers then afforded diol 12, which was subjected to bromination with PhNMe 3 Br 3 to deliver the desired product with d.r.…”