Regiospecific synthesis of 1,7-dialkylthiocycloheptatrienes. A case of rapid [1,7] sigmatropic migration of unhindered alkylthio-groups

Abstract

Die Alkylthiotropenyliumperchlorate (I) liefern mit den Mercaptiden (II) die Dialkylthiocycloheptatriene (III), deren Alkylthiogruppen bei Raumtemperatur über die Zwischenstufen (IV) austauschen.

Synthesis of (7-(alkylthio)- and 7-(arylthio)cycloheptatriene)tricarbonyliron and -hexacarbonyldiiron complexes

“…This was done both on the intact mixture after 75 min of stirring and on the residue after solvent evaporation at reduced pressure; only a trace of diphenyl disulfide was identified, possibly arising from air oxidation of thiophenol. l,2-[Bis(7-thiocycloheptatrienyl)tricarbonyliron]ethane (6). To a solution of 3 (0.530 g, 2.15 mmol) in methanol (20 mL) were added with stirring under nitrogen at room temperature 1,2-ethanedithiol (0.20 mL, 2.4 mmol) and boron trifluoride etherate (0.27 mL, 2.15 mmol).…”

“…Caled for C10H12C1N-HC1: C, 55.06; , 6.01; N, 6.42; Cl, 32.51. Found: C, 55.14; , 6.01; N, 6.42; Cl, 32.17.…”

Revival of troponoid chemistry

“…Another interesting point concerns the serendipitous discovery of 21, = 2 or 3, during attempted dithioketalization of tropone.34 This inspired the synthesis of 22, 23, 24, and close analogues by reaction, at low temperature, respectively, of methoxytropenylium with methanethiolate, methylthiotropenylium with butanethiolate, and butylthiotropenylium with methanethiolate ion. 35 Interestingly, 23 and 24 in chloroform solution undergo interconversion of the alkylthio groups at C-l and C-7. At room temperature the equilibrium composition at 44% 23 and 56% 24 was reached in ~6 h. 36 These results can be rationalized in terms of a rapid [1,7] sigmatropic shift of alkylthio groups.…”