Synthesis of Poly(2-substituted-1-propenylene)s from Allylic Arsonium Ylides

Abstract

The polymerization of several allylic triphenylarsonium ylides, which contain a pendant R group at the 2-position, in the presence of triethylborane, is described. Three initial molar ratios of ylide to triethylborane (15, 30, 60) were used, leading to different degrees of polymerization. The ylide was generated from the corresponding arsonium salt, in THF at −78 °C, using either tert-butyllithium (when R = alkyl) or lithium hexamethyldisilazide (when R = tBuMe2SiOCH2CH2−) as the base. After addition of triethylborane at 0 °C, the deep-red solution of ylide was readily discolored. Then oxidation of the resulting polymeric borane led to linear skipped polyenes containing a terminal alcohol function. These polymers can be called poly(2-substituted-1-propenylene)s. Molecular weights have been determined from both 1H NMR analyses and size exclusion chromatography (SEC). In most cases, the molecular weight of the polymers increases linearly with the initial ylide/triethylborane molar ratio, which gives credit to a controlled polymerization process. Block copolymers were also obtained from triethylborane by successive additions of two different 2-substituted allylic arsonium ylides, followed by oxidation (yield: 62−85%).

Enantiocontrolled Synthesis of β‐Branched α‐Amino Acids by Using CuI‐Catalyzed 1,4‐Addition of Glycine Imines to β‐Substituted gem‐Diactivated Olefins

“…Charles leistete viele bedeutende Beiträge zur organischen und bioorganischen Chemie. Ihm sind wichtige Fortschritte bei Synthesemethoden zu verdanken, besonders in Bezug auf die Reaktivität von Epoxiden1 sowie von Sulfonium‐ und Arsenium‐Yliden 2. Ebenfalls hervorzuheben sind seine Arbeiten über Organophosphor‐ und Organoborreagentien3 sowie – in Zusammenarbeit mit seinem Freund J. R. Falck – über chromvermittelte Reaktionen,4 in deren Rahmen er erst kürzlich Chromcarbinkomplexe als vielseitige Intermediate in die organische Synthese einführte.…”

Boron‐Catalyzed Polymerization of Dienyltriphenylarsonium Ylides: On the Way to Pure C5 Polymerization

“…It is worth noting that the polymerization would not proceed exactly in the same manner along with the three arms due to the random polymerization. It cannot be excluded that the polymerization may not occur or be slower for one of the three arms, [4a] thus explaining why the molecular weights of polymer 1 are higher than theoretical ones (Table 1, entries 3,4). The higher experimental molecular weights may also be due to the deactivation of a small amount of triethylborane (accidental air oxidation).…”

Terpolymers from Borane‐Initiated Copolymerization of Triphenyl Arsonium and Sulfoxonium Ylides: An Unexpected Light Emission

“…However, this monomer did not lead to polymer substituted on every one carbon atom (C1), but rather on every three carbon atoms (C3 polymerization), meaning that the chain is growing by three carbon atoms at a time. In 2005, the same authors realized that a few other 2‐allylsubstituted triphenylarsonium ylides show the same behavior . Later, Mioskowski et al.…”