New hexahydro-2H-chromenes were synthesized by reactions of monoterpenoid (1R,2R,6S)-3-methyl-6-(prop-1-en-2-yl)cyclohex-3-ene-1,2-diol with aliphatic ketones in the presence of montmorillonite clay H⁺-K10. The compounds formed and isolated as a pair of diastereoisomers were evaluated for their analgesic activity in vivo. It was found that the analgesic activity of (4aR,8R,8aR)-4,7-dimethyl-3,4,4a,5,8,8a-hexahydrospiro[chromene-2,1ʹ-cyclohexane]-4,8-diol 8b significantly exceeds (two orders of magnitude higher) the activity of diclofenac sodium in the acetic acid-induced writhing test. It has low acute toxicity and is very promising for further development.

中文翻译：

---

脂肪族酮衍生的手性六氢-2 H-色烯的合成及止痛活性

通过单萜类化合物（1 R，2 R，6 S）-3-甲基-6-（prop-1-en-2-yl）cyclohex-3-ene-1,2的反应合成了新的六氢-2 H-色烯蒙脱石粘土H ⁺ -K10存在下，具有脂肪族酮的α-二醇。评价形成和分离为一对非对映异构体的化合物的体内止痛活性。发现（4a R，8 R，8a R）-4,7-二甲基-3,4,4a，5,8,8a-六氢螺[铬烯-2,1′-环己烷] -4的镇痛活性， 8-二醇8b大大超过了乙酸诱导的扭体试验中双氯芬酸钠的活性（高出两个数量级）。它的急性毒性低，对进一步开发很有前景。