Annulenoide Tetrathiafulvalene:, 5,16-Bis(1,3-benzodithiol-2-yliden)-5,16-dihydrotetraepoxy- und 5,16-Bis(1,3-benzodithiol-2-yliden)-5,16-dihydrotetraepithio[22]annulene(2.1.2.1)

Abstract

Annulenoid Tetrathiafulvalenes: 5,16-Bis(1,3-benzodithiol-2-ylidene)-5,16-dihydrotetraepoxy-and 5,16-Bis(1,3-benzodithiol-2-ylidene)-5,16-dihydrotetraepithio[22]annulenes(2.1.2.1) The title compounds are among the first tetrathiafulvalenes with annulene spacers, here with tetraepoxy-[22]annulene(2.1.2.1) (see 3a), tetraepithio[22]annulene(2.1.2.1) (see 3b), and diepithiodiepoxy[22]annulene(2.1.2.1) (see 23) units. The annulenoid tetrathiafulvalenes 3a and 3b are prepared by cyclizing McMurry coupling of the 5,5'-(1,3-benzodithiol-2-ylidenemethylene)bis[furan-or thiophene-2-carbaldehydes] (8a or 8b, resp.) or by Wittig reaction of (1,3-benzodithiol-2-yl)tributylphosphonium tetrafluoroborate (13b) with tetraepoxy[22]annulene(2.1.2.1)-1,12-dione 20 (formation of 3a) or diepithiodiepoxy[22]annulene(2.1.2.1)-1,12-dione 22 (formation of 23). The annulenoide tetrathiafulvalene 3a is obtained as a mixture of the isomers (E,E)-and (Z,Z)-3a. At 1308, (Z,Z)-3a rearranges quantitatively into the (E,E)-isomer. Isomer (E,E)-3a is a dynamic molecule, where the (E)-ethene-1,2-diyl bridges rotate around the adjacent s-bonds. The tetraepithioannulene derivative 3b as well as 23 only exist in the (Z,Z)-configuration. The oxidation of (E,E/Z,Z)-3a with Br 2 yields the annulene-bridged tetrathiafulvalene dication (E,E)-3a Ox , while with 4,5-dichloro-3,6dioxocyclohexa-1,4-diene-1,2-dicarbonitrile (DDQ) obviously only the radical cation 3a Sem is formed, which belongs to the class of cyanine-like violenes. The annulenoide tetrathiafulvalenes 3b and 23, which exist only in the (Z,Z)-configuration, obviously for steric reasons, cannot be oxidized by DDQ. Electrochemical studies are in agreement with these results.Helvetica Chimica Acta ± Vol. 84 (2001) Schema 1 2. Synthese der 5,16-Bis(1,3-dithiol-2-yliden)-5,16-dihydrotetraepoxy-und 5,16-Bis(1,3-dithiol-2-yliden)-5,16-dihydrotetraepithio[22]annulene(2.1.2.1) 1 ) 2 und 3. ± 2.1. Strategie. Das Konzept der Synthese von 2 und 3 geht aus von Difurylketon 4a und Dithienylketon 4b, die durch Wittig-Reaktionen in die 1,3-Dithiol-4,5-dicarbonitrile 5a und 5b und die 1,3-Benzodithiole 6a und 6b überführt werden sollen (Schema 2). Durch Formylierung von 5 und 6 zu den Diformyl-substituierten 1,3-Dithiol-4,5-dicarbonitrilen 7a und 7b und 1,3-Benzodithiole 8a und 8b und anschliessende McMurry-Cyclisierungen sollten die annulenoiden Tetrathiafulvalene 2 und 3 zugänglich sein. 2.2. Zwischenprodukte 7a,b. Die Ketone 4a und 4b als Edukte der Synthesesequenz wurden durch Umsetzung von 2-Furyllithium bzw. 2-Thienyllithium mit Dimethylcarbamidsäure-ethylester [17] hergestellt [18]. Zur Synthese von 1,3-Dithiol-4,5-dicarbonitril 5a wurde die Kondensation von Keton 4a mit 2-Thioxo-1,3-dithiol-4,5-dicarbonitril (11) [19] in Gegenwart von Triphenylphosphin (PPh 3 ) untersucht. In der Literatur war bereits die Olefinierung von Benzaldehyd [20] und Aceton [21] mit 11/PPh 3 beschrieben worden. Diese Umsetzungen verlaufen nach Corey [22] über das aus 11 nach Entzug des Thioxo-S-Atoms mit PPh 3 gebildeten Phospho...

Oligomeric and Polymeric Systems with a Cross-conjugated π-Framework

“…182 Several years later, Märkl and co-workers prepared cross-conjugated macrocycles 234-236 based on dithiafulvene subunits with annulene spacers, also using the McMurry coupling. 183 Compound 234 was obtained as a mixture of (E,E)-and (Z,Z)-isomers that could be converted thermally to the (E,E)-isomer.…”

“…The first cross-conjugated macrocycle based on an arylene vinylene spacer, 233 , was synthesized by Kawase and Oda via a McMurry coupling reaction and served as a synthetic precursor to a Fritsch−Buttenberg−Wiechell rearrangement (Scheme ) . Several years later, Märkl and co-workers prepared cross-conjugated macrocycles 234 − 236 based on dithiafulvene subunits with annulene spacers, also using the McMurry coupling . Compound 234 was obtained as a mixture of ( E,E )- and ( Z,Z )-isomers that could be converted thermally to the ( E,E )-isomer.…”

Olefination Reactions in the Synthesis of Cyclophanes

“…Furan‐ and thiophene‐based [2.1.2.1](2,5)heteraphanedienes 145 a – e were synthesized from the corresponding dialdehydes 144 a – e using three different sets of McMurry reaction conditions (Scheme ). The yields were either very good (70–75 % for 145 a 85 and 145 b 95) or quite low (10–15 % for 145 c 96 and 145 d – e 97). Whereas the high variability of the yields does not correlate with the nature of the heteroaromatic system, the formation of the E,E isomer in the product was observed only for the furan‐based cyclophanes 145 c – d 98.…”

The McMurry Coupling and Related Reactions

“…The tandem McMurry reaction has been successfully used for the synthesis of cyclophanes (Figure 6.22; Table 6.8) such as 133 and 134 [114,115,173], and is a classical route to ''expanded'' porphyrin systems. After the preparation of porphycene and its substituted derivatives such as 135 [174], a variety of porphyrin analogues were isolated, in which pyrrole units were replaced with furan or thiophene rings and/or extended by additional ring systems [135,[175][176][177][178][179][180][181][182][183][184][185] 6.24). Some of these molecules are of current interest as effective photosensitizers for biomedical applications and are employed in the photodynamic therapy of tumors and viral inhibition.…”