Radikalische Additionen, X: Einfache Synthese einiger Spiro[2.4]heptan‐4,4,7,7‐tetracarbonitrile

Abstract

propanedinitriles (4) and 2-(1-alkyl-2-bromopropylidene)propanedinitriles (5) can be easily synthesized by free radical additions of bromomalononitrile ( 2 ) to allenes (1). some compounds 5 also by bromination of alkylidenepropanedinitriles. 4a -c and 5a, b are converted with triethylamine at room temperature (70-80%) to the spiro[2.4]heptane-4,4,7,7-tetracarbonitriles 8 -10. The structure of 9 was proved by X-ray analysis. The 9-ring of 9 is strongly twisted with bond angles for some saturated C-atoms of nearly 120" and bond lengths of 148.5 pm.Alkylhalogenide lassen sich radikalisch an Allene (1) addieren. Brommalononitril (2) liefert dabei iiberwiegend die Produkte, die durch Angriff eines Dicyanmethyl-Radikals am sp-C-Atom entstehen (4)l). Die Verbindungen 4 lagern sich leicht in die Tautomeren 5 um.Da die Additionsprodukte des Brommalononitrils an Alkene (6) bereits mit schwachen Basen wie Triethylamin glatte 1,3-HBr-EIirninierung zu Cyclopropan-1 ,1 -dicarbonitrilen (7) g e b e~~* -~) , sollte die Umsetzung der Verbindungen 4 mit Basen untersucht werden.4a lieferte mit Triethylamin ein farbloses kristallisiertes Produkt, das nach der Molekiilmasse (MS) und aufgrund der Elementaranalyse die Summenformel C,,H,,N, besitzt und demnach aus zwei Molekiilen 4 a unter Abspaltung von zwei Molekiilen HBr Chem. Ber. 114(1981)

Practical Radical Additions under Mild Conditions Using 2,2‘-Azobis(2,4-dimethyl-4-methoxyvaleronitrile) [V-70] as an Initiator

“…2-(2-Bromo-2-phenylethyl)malononitrile ( 3a ): (79% yield, as white crystals) mp 60.2−61.8 °C (lit 4b. 60.5−61.0 °C); 1 H NMR (CDCl 3 ) δ 2.82 (m, 2 H), 4.01 (dd, 1 H, J = 6, 10 Hz), 5.08 (dd, 1 H, J = 6, 10 Hz), 7.41 (bs, 5 H); MS m / z (%) 250 (M + + 2, 2), 248 (M + , 2), 104 (100); HRMS calcd for C 11 H 9 79 BrN 2 247.9949, found 247.9948.…”

“…2-(2-Bromo-1,2-dimethylpropyl)malononitrile ( 3c ): (81% yield, as white crystals); mp 40.5−41.9 °C (lit 4b. 41.0−41.5 °C); 1 H NMR (CDCl 3 ) δ 1.43 (d, 3 H, J = 7 Hz), 1.82 (s, 3 H), 1.91 (s, 3 H), 2.59 (dq, 1 H, J = 7, 2 Hz), 4.59 (d, 1 H, J = 2 Hz).…”

“…2-(2-Bromo-1,1,2-trimethylpropyl)malononitrile ( 3d ): (84% yield, as white crystals); mp 115.4−116.2 °C (lit 4b. 117−117.5 °C); 1 H NMR (CDCl 3 ) δ 1.46 (s, 6 H), 1.95 (s, 6 H), 4.45 (s, 1 H).…”

“…On the other hand, photoinduced radical addition reactions are generally run at ambient temperatures. Additions of malononitrile radical induced by photoirradiation to alkenes are carried out successfully at room temperature, but photochemical reactions are sometimes accompanied by difficulties such as practicability for large-scale productions. To evade these drawbacks, we intended to take advantage of 2,2‘-azobis(2,4-dimethyl-4-methoxyvaleronitrile) [V-70] 5 which is known as an effective initiator in the synthesis of polymers .…”

Crystal and Molecular Structures of Trifluoroacrylonitrile, F2CCF−CN, and Trifluorovinyl Isocyanide, F2CCF−NC, by Low-Temperature X-ray Crystallography and ab Initio Calculations

“…18 The CsCtN bond angle in the cyanide and the CsNtC bond angle in the isocyanide were held at 180°. This is a satisfactory approximation, because the molecular structure determinations of various isocyanides [19][20][21][22][23] and nitriles 19,[24][25][26] have shown little or no deviation from 180°of these bond angles. Whereas in the crystal structures of transition metal complexes of isocyanides 27 and nitriles, 28 the CsNsC angle is more flexible than the corresponding angle (CsCsN) in nitriles (cyanides) for both steric and electronic reasons.…”