1,8-Bis(tetramethylguanidino)naphthalene (TMGN, 1) is a new, readily accessible, and stable "proton sponge" with an experimental pK(BH(+)) value of 25.1 in MeCN, which is nearly seven orders of magnitude higher in basicity than the classical proton sponge 1,8-bis(dimethylamino)-naphthalene (DMAN). Because of the sterically less crowded character of the proton-accepting sp(2)-nitrogen atoms, TMGN also has a higher kinetic basicity than DMAN, which is shown by time-resolved proton self-exchange reactions. TMGN is more resistant to hydrolysis and is a weaker nucleophile towards the alkylating agent EtI in comparison to the commercially available guanidine 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD). Crystal structures of the free base, of the mono- and bisprotonated base were determined. The dynamic behavior of all three species in solution was investigated by variable-temperature (1)H NMR experiments. DeltaG (++) values obtained by spectra simulation reveal a concerted mechanism of rotation about the C-N bonds of the protonated forms of TMGN.

中文翻译：

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1,8-双（四甲基胍基）萘（TMGN）：一种新型的，具有超碱性和动力学活性的“质子海绵”。

1,8-双（四甲基胍基）萘（TMGN，1）是一种新的，易于使用且稳定的“质子海绵”，在MeCN中的实验pK（BH（+））值为25.1，约为七个数量级碱性比经典的质子海绵1,8-双（二​​甲基氨基）-萘（DMAN）高。由于接受质子的sp（2）-氮原子在空间上不那么拥挤，TMGN还具有比DMAN更高的动力学碱性，这在时间分辨的质子自交换反应中得到了证明。与市售的胍7-甲基-1,5,7-三氮杂双环[4.4.0]癸-5-烯（MTBD）相比，TMGN对水解的抵抗力更强，并且对烷基化剂EtI的亲核力更弱。确定了游离碱，单和双质子化碱的晶体结构。通过变温（1）H NMR实验研究了溶液中所有三种物质的动力学行为。通过光谱模拟获得的DeltaG（++）值揭示了围绕TMGN的质子化形式的CN键旋转的协调机制。