## 2 Results and Discussion  
The starting compounds, 8-quinolinesulfenyl chloride **3** and bromide **4**, were generated in situ from di(8-quinolinyl) disulfide **(2)** in methylene chloride or chloroform and used without isolation in further reactions with alkenes and natural products (eugenol derivatives, _trans_-anethole) (Scheme 2). **Scheme 2. ** The generation of 8-quinolinesulfenyl chloride **3** and bromide **4** from di(8-quinolinyl) disulfide **2** by the action of sulfuryl chloride or bromine. Taking into account the known data on the reactions of 8-quinolinesulfenyl halides with cycloalkenes [33], which produced electrophilic addition products of sulfenyl chloride **3** and annulation products in the case of sulfenyl bromide **4** (Scheme 1), it could be assumed that the reactions of 8-quinolinesulfenyl halides with 1-alkenes would proceed similarly. However, the reactions of sulfenyl chloride **3** with 1-alkenes gave a complex mixture of compounds including electrophilic addition products under the same conditions as indicated in Scheme 1. Nevertheless, the reactions of sulfenyl bromide **4** with 1-alkenes at room temperature in methylene chloride led to annulation products **5** and **6** in 85% and 81% yields, respectively (Scheme 3). Compounds **5** and **6** are water-soluble light-yellow powders with a melting point of about 120 \({}^{\circ}\)C.  
The naturally occurring products eugenol (4-allyl-2-methoxyphenol) and isoeugenol (2-methoxy-4-(1-propenyl)phenol) were involved in the annulation reactions with 8-quinolinesulfenyl chloride **3**. The reaction of sulfenyl chloride **3** with isoeugenol smoothly proceeded at room temperature in chloroform, giving compound **7** in a 90% yield (Scheme 4). The reaction of sulfenyl chloride **3** with eugenol under the same conditions as the synthesis of compound **7** was very sluggish (40% yield of the annulation product). However, carrying out the reaction of sulfenyl chloride **3** with eugenol under reflux in chloroform for 7 h allowed us to obtain annulation product **8** in a 75% yield (Scheme 4). The reaction of sulfenyl chloride **3** with eugenol includes electrophilic addition of the sulfur atom of sulfenyl electrophile to the \(\alpha\)-carbon atom of the vinyl group (the anti-Markovovikov direction), while the opposite regiochemistry is observed in the annulation reaction of sulfenyl chloride **3** with isoeugenol. Another naturally occurring compound, _trans_-anethole (1-methoxy-4-(E-1-propenyl) benzene), appears to be very reactive in annulation reactions. The reaction of sulfenyl chloride **3** with _trans_-anethole was carried out at room temperature in methylene chloride, affording quinolinium chloride **9** in a quantitative yield (Scheme 5). The reaction of sulfenyl chloride **3** with methyl eugenol (4-allyl-1,2-dimethoxyobenzene) seems to proceed more slowly than with eugenol. Under the same conditions as the synthesis of product **9**, the reaction of sulfenyl chloride **3** with methyl eugenol afforded the annulation product in a 57% yield. However, after refluxing the mixture of sulfenyl chloride **3** with methyl eugenol in chloroform for 3 h, annulation product **10** was obtained in a 98% yield (Scheme 5). The double bond in _trans_-anethole and isoeugenol occurs in conjugation with the benzene ring, and these compounds demonstrate higher activity in the annulation reactions compared to eugenol and methyl eugenol bearing the allyl fragment without conjugation of the double bond. Such substrates as styrene, 4-methylstyrene and \(\alpha\)-methylstyrene and \(1H\)-indene also have the double bond, which is in conjugation with the benzene ring. We assumed that these substrates may be active in the annulation and carried out the reactions of sulfenyl chloride **3** with them. The reactions of quinoline sulfenyl chloride **3** with styrene proceeded smoothly in methylene chloride at room temperature for 24 h to give quinolinium chloride **11** in a 97% yield (Scheme 6).