Silyl Tosylate Precursors to Cyclohexyne, 1,2-Cyclohexadiene, and 1,2-Cycloheptadiene

Abstract

Transient strained cyclic intermediates have become valuable intermediates in modern synthetic chemistry. Although silyl triflate precursors to strained intermediates are most often employed, the instability of some silyl triflates warrants the development of alternative precursors. We report the syntheses of silyl tosylate precursors to cyclohexyne, 1,2-cyclohexadiene, and 1,2-cycloheptadiene. The resultant strained intermediates undergo trapping in situ to give cycloaddition products. Additionally, the results of competition experiments between silyl triflates and silyl tosylates are reported.

Regiospecific substitution of the β-vinylic sp2 carbon of cyclohexenones bearing the α-chloro- and β-tosylate-groups: Single crystal XRD/Hirshfeld surface/in-silico studies of three representative compounds

“…In general, α,β-unsaturated ketones are well recognized to be polarized with the separation of a discrete negative charge on the oxygen and corresponding positive charge on the βvinylic carbon. In the reactant molecule 3, this renders the carbon-tosylate bond to cleave easily, rendering the tosylate group to become a good leaving group [21]. Further, the present study, in comparison to our earlier report [5] clearly indicates that between the bromo and the tosylate substituents, the reactivity of the tosylate group is slightly lesser when compared to the bromo substituent.…”

Synthesis, antimicrobial/radical scavenging, and in‐silico investigations of a novel class of 4‐[(4′‐hydroxymethylphenyl)‐1H‐1′,2′,3′‐triazol‐1‐yl‐methyl]‐2H‐chromen‐2‐ones

“…In this regard, TBAF is a commercially available reagent and used as a fluoride source to cleave silicon-carbon bond thereby generating in-situ carbanions that may react with electrophiles [8]. We have found that in our reaction conditions, TBAF has proved to be an excellent desilylating agent [9]. The reaction of 1a-j and TBAF in the presence of benzaldehyde afforded the substitution products: the secondary alcohols 2a-j in greater than 88% isolated yields.…”

Origins of Endo Selectivity in Diels–Alder Reactions of Cyclic Allene Dienophiles

“…A diverse range of stereochemically‐rich products can be accessed via highly endo selective Diels–Alder cycloadditions to strained cyclic allenes, as shown by cycloadducts 1 – 4 (Figure 1 a). [2b–e] Our groups [2c,d,f–i] and others [2j,k] have generated strained cyclic allenes from silyl triflates, 5 , and have found that in situ generated heterocyclic allenes, such as unsubstituted allenes 7 and 8 , participate in highly endo selective Diels–Alder reactions to provide adducts 13 – 22 (Figure 1 b). [2c,d] …”