Mećhanistic dichotomy in cycloadditions to cyclooctatetraeneiron tricarbonyl. X-ray crystal structure analysis of the TCNE and CSI adducts

Metal-Assisted Cycloaddition Reactions in Organotransition Metal Chemistry

“…As opposed to Green and Wood, 391 Olsen not only finds the Diels-Alder adduct 375, but also the barbaralone derivative 378, implying that besides [4+2] addition also [3+2] addition (376, path B) with consecutive CO insertion (377) and reductive elimination takes place. This alternative reaction mode has already been discussed with TCNE as twoelectron component in section II.C.1, and structure 394 have also reported a case of [4+2] addition of chlorosulfonyl isocyanate to 374, as opposed to the [3+2] addition mode of TCNE.…”

“…The cycloaddition reactions of cyclic triene complexes 161 (eq 52) related to (η 4 -cycloheptatriene)Fe(CO) 3 or (COT)Fe(CO) 3 with reactive dienophiles such as tetracyanoethylene (TCNE), 4-phenyltriazoline-3,5-dione (NPTD), or hexafluoroacetone (HFA) have been studied by several groups. −

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Synthesis, Chiroptical Properties, and Absolute Configuration of (+)-2,3-Dihydrotriquinacen-2-one. Effect of Rigid Triquinacene Geometry on the Inherently Dissymmetric Chromophore

“…Sealed Tube Conditions. Tetranitrile 75,6 (2.0 g, 8.62 mmol) was heated together with concentrated hydrochloric acid (20 ml) in a thick-walled sealed tube at 130°for 11 hr. The tube was cooled to -77°before opening (Caution: because of the liberation of 2 equiv of carbon dioxide, there is considerable internal pressure which is released; suitable safety protection should be taken).…”

“…This aqueous phase was washed with dichloromethane (3X15 ml), then carefully acidified by the dropwise addition of concentrated hydrochloric acid. The mixture was extracted with dichloromethane (3 X 20 ml), dried, and evaporated under reduced pressure to afford• white crystals (from ether) of the hydroxy acid: mp 152-153°( 321 mg, 68.5%); vmax (CHC13) 3500-2500 and 1680 cm'1; ¿Mc4s¡ (CDCl3/Me2SO-¿6) 7.7 (br s, 1), 6.75 (br d, 1), S.5-5.9 (m, 2), 4.1-4.6 (m, 1), 3.5-3.9 (m, 1), 2.6-3.5 (m, 4), and 1.2-2.4 (m, 2).…”

Recent developments in the synthetic uses of chlorosulfonyl isocyanate

“…54 Similarly, the dihydroquinolines 145 and 147 are reported to give the nitriles 146 and 148 (eq 41, 42). No evidence as to the nature of the intermediates was given.55 154 + R1C02" (46) The /3-lactam 149 obtained from CSI and 1,3-dioxole in quantitative yield is reported to decompose on attempted purification. Dihydro-p-dioxin, however, produces only the unstable amide 150.56 C0NHS02CI 150 Ketene thioacetal 151 undergoes ready reaction with CSI; once again, however, only the open chain amide 152 is formed.57…”