The questionable mechanism initially proposed to explain how 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) allows us to ring-open β-lactones, such as β-butyrolactone (BL), is reinvestigated here. With the use of a trisubstituted β-lactone, i.e. (R,S)-benzylcarbonyl-3,3-dimethyl-2-oxetanone, and the association of techniques such as ¹H/DOSY NMR and MALDI/ESI-MS, we demonstrated that BL is effectively polymerized by the TBD in bulk at 60 °C, minorly from the reported N-acyl-α,β-unsaturated TBD species, and majorly from crotonate anions issued from the basic activation of BL. In contrast to what has been reported, the TBD is not covalently linked to the PBL chain but mainly plays the role of a counterion in the –C(O)O⁻, TBDH⁺ active site.

中文翻译：

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从1,5,7-三氮杂双环[4.4.0] dec-5-ene †合成β-丁内酯聚合机理的再研究

最初提出的可疑机制用于解释1,5,7-三氮杂双环[4.4.0] dec-5-ene（TBD）如何使我们将β-内酯开环，例如β-丁内酯（BL），在此进行了重新研究。 。通过使用三取代的β-内酯，即（R，S）-苄基羰基-3,3-二甲基-2-氧杂环丁酮，以及诸如¹ H / DOSY NMR和MALDI / ESI-MS之类的技术的结合，我们证明了该BL是通过散装TBD在60℃有效地进行聚合，minorly从报告的ñ-酰基-α，β-不饱和的TBD物种，并且主要来自BL的基本活化所产生的巴豆酸根阴离子。相较于已报告的TBD不共价连接到PBL链，但主要起到在-C（O）O的抗衡作用^-，TBDH ⁺活性位点。