Synthesen einiger alkyl-substituierter cyclobutadien-nickel(II)-chloride

Cyclobutadienemetal complexes

“…The treatment of the latter SCHEME F62(CO)q Ĉr(CO)6 Et20 hv 0 -Fe(CO)3 X/ --Cr(CO)4 with HCI affords a mixture of dichlorocyclobutene isomers (22)53 with vicinal dimethyl substituents. Bruñe and his co-workers had employed the dichlorocyclobutenes (22), synthesized by the above cited procedure, in the preparation of an extensive series of iron (23) and nickel (24) cyclobutadiene complexes including 23 [Rt = R2 = H;54 R1 = H, R2 = Me;54 R^= R2 = Me54 (the same as 7);49 Rt = R2 = Et;55 Ri = Me, R2 = Et;55 R: = R2 = /-Pr;56 Rt = Me, R2 = /-Pr;56 R, = H, R2 = Et;57 R1 = H, R2 = i-Prj58 and 24 [R3 = R2 = H; R-, = H, R2 = Me; R-, = Me, R2 = Et; R-i = Me, R2 = /-Pr; R-i = R2 = Et; Rt = R2 = z'-Pr] , 59 In one instance, the individual isomers of 22 (Rt = R2 = H) [trans-3.4dichloro-1,2-dimethylcyclobutene (22a), frans-3,4-di-3hloro-2,3-dimethylcyclobutene (22b), and frans-3,4-dichloro-3.4dimethylcyclobutene (22c)] were separated and their reactions with Fe2(CO)9 followed. It was found60 that both 22a and 22b reacted with Fe2(CO)9 to afford 23 (R-= R2 = H), whereas, the sole organometallic product from a similar reaction with 22c was the dibridged acyl tetracarbonyliron complex 25 which under thermal conditions at 140 °C could be converted to 23 (R1 = R2 = H) (Scheme V).…”

Mechanism of the thermal extrusion of sulfur dioxide from (.eta.5-cyclopentadienyl)cobalt .eta.4-thiophene 1,1-dioxides to complexed cyclobutadienes

“…2-Acetyl-5-methylthiophene (8). A 300-mL three-neck round-bottom flask was fitted with a thermometer, a 50-mL addition funnel, a magnetic stirring bar, and a CaCl2 drying tube.…”

“…2-Ethyl-5-methylthiophene (9). 2-Acetyl-5-methylthiophene (8) (7.806 g, 0.0557 mol) and hydrazine hydrate (85% NH2NH2, 9.48 g, 0.189 mol) were added to ethylene glycol (100 mL) in a 200-mL three-neck round-bottom flask. The latter was fitted with a thermometer, a glass stopper, reflux condenser, and magnetic stirring bar.…”

“…Complex 7 was obtained by the sequence of reactions shown in Scheme II. 2-Acetyl-5-methylthiophene (8), prepared by acylation of 2-methylthiophene, was reduced by the Wolff-Kishner method to give 2ethyl-5-methylthiophene (9). The latter was converted to the 1,1-dioxide 10 with m-chloroperbenzoic acid.…”