Intramolecular cyclization of [o-(arylthio)phenyl]ethenes. synthesis and crystal structure of 1-arylbenzo[b]thiophenium salts

From Colorless to Near-Infrared S-Heteroarene Isomers: Unexpected Cycloaromatization of Cyclopenta[b]thiopyran Catalyzed by PtCl2

“…The lengths of S–C bonds in isomers 6a and 6b range from 1.7103 to 1.7405 Å (Tables S3 and S4), which are typical bond lengths for S–C bonds in the thiophene ring, whereas the lengths of S–C bonds in the thiopyran ring of 6c are 1.7158(18) and 1.7376(17) Å, respectively (Table S5). Similar to those in the thiophene rings of isomers 6a and 6b , these values are between the lengths of well-acknowledged S–C single (1.778–1.882 Å) and double bonds (1.553–1.611 Å) . This suggests that the lone pair electrons of the sulfur atoms are involved in the π-conjugated backbone of isomer 6c .…”

Facile Synthesis of S‐Fused Multi‐Membered Polycyclic Heterocycles: A Construction Strategy towards Thermally Stable Thiepine Derivatives

“…Moreover, the molecule of S6 displays a planar structure with dihedral angles of two adjacent rings less than 3°. The lengths of the two S—C bonds in the thiopyran ring of S6 are 1.733(2) and 1.743(2) Å, respectively (Table S2), which are in between the lengths of well‐acknowledged S—C single (1.778—1.882 Å) [ 29 ] and double bonds (1.553—1.611 Å). [ 30 ] This suggests the effective conjugation extension through the lone pair electrons of the sulfur atom of thiopyran in S6 , which contributes to the aromatic characteristics of cyclopenta[ b ]thiopyran moiety due to its 10 π‐electrons, perfectly matching Hückel's rule.…”

Selective 6-endo-dig and ring-expansion cycloisomerizations of ortho-disubstituted thiophenes bearing 1-en-3-yne moieties

“…1c displays the bond lengths for the benzo[ b ]thiophene and cyclopenta[ c ]thiapyran cores of compounds 3b and 4a , respectively. The lengths of all the S–C bonds in 3b and 4a are in the range of 1.713–1.737 Å, which lie between the values for a typical S–C single bond (1.778–1.882 Å) 32 and a double bond (1.553–1.611 Å), 33 which suggests that the lone pair electrons on the S atoms are involved in the π-conjugated backbones of both benzo[ b ]thiophene and cyclopenta[ c ]thiapyran. Moreover, the lengths of the S–C bonds in 3b are slightly longer than those in 4a , indicating that the S–C bond is more delocalized in cyclopenta[ c ]thiapyran than in benzo[ b ]thiophene.…”