Depending on the selected synthetic pathway, structural variations of the neurotransmitter histamine led to mixtures of alpha,beta-dimethylhistamines as well as to the corresponding pure optical isomers. One of these isomers, namely (alpha R,beta S)-alpha,beta-dimethylhistamine, proved to be a highly potent H3 receptor agonist with exceptional receptor selectivity. The absolute configuration of the compound was determined by X-ray structure analysis of its dihydrobromide using the anomalous dispersion of bromine. The optical purity of both enantiomers of erythro-alpha,beta-dimethylhistamine was checked by 1HNMR investigations after acylation of the amines with (R)-2-methoxy-2-phenylacetyl chloride. As expected H3 receptors distinguish in a very strong way between the title compound and its alpha S,beta R-configured enantiomer. The agonistic potency of the latter is 2 orders of magnitude lower than the potency of (alpha R,beta S)-alpha,beta-dimethylhistamine.

中文翻译：

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（αR，βS）-α，β-二甲基组胺，一种新型的高效组胺H3受体激动剂的合成，绝对构型，立体选择性和受体选择性。

取决于选择的合成途径，神经递质组胺的结构变化导致α，β-二甲基组胺的混合物以及相应的纯光学异构体。这些异构体之一，即（αR，βS）-α，β-二甲基组胺，被证明是一种高效的H3受体激动剂，具有出色的受体选择性。使用溴的反常分散体，通过对其二氢溴化物的X射线结构分析来确定化合物的绝对构型。用（R）-2-甲氧基-2-苯基乙酰氯将胺酰化后，通过1 HNMR研究检查赤型-α，β-二甲基组胺的两种对映体的光学纯度。正如预期的那样，H3受体在标题化合物与其α-S，β-R-对映体之间有非常强的区别。