AsymmetricSimmons-Smithreactions of α,β-unsaturated acetals derived from chiral dialkyl tartrate or (2R,4R)-2,4-pentanediol are described. Treatment of the acetal with diethylzinc and methylene iodide gives a cyclopropane with high diastereoselectivity. The acetal group is readily transformed to the aldehyde or the ester group. In addition, the method is successfully applied to the enantioselective
Simple, Mild and Efficient Thioacetalization and Transthioacetalization of Carbonyl Compounds and Deprotection of Thioacetals: Unique Role of Thiols in the Selectivity of Thioacetalization
Silicasupportedsodiumhydrogen sulfate (NaHSO 4 .SiO 2 ) has been employed for efficient thioacetalization and transthioacetalization of carbonyl compounds in CH 2 Cl 2 at room temperature. Selectivity of thioacetalization was dependent on the thiols used for the conversion. The same catalyst was also found to be effective for deprotection of thioacetals in CH 2 Cl 2 -H 2 O at room temperature.
Reactions d'addition sur les composes carbonyles, allylation, arylation, vinylation et acylation en presence ou non de catalyseurs
反应 d'addition sur les 组成羰基、烯丙基化、芳基化、乙烯基化和酰化在非脱催化剂的存在下
Chemical Library and Structure–Activity Relationships of 11-Demethyl-12-oxo Calanolide A Analogues as Anti-HIV-1 Agents
作者:Tao Ma、Li Liu、Hai Xue、Li Li、Chunyan Han、Lin Wang、Zhiwei Chen、Gang Liu
DOI:10.1021/jm701405p
日期:2008.3.13
(+)-Calanolide A (1) as a natural product was previously found as an inhibitor of HIV-1 reverse tratiscriptase. In our further investigation of its template, racemic 11-demethyl-12-oxo calanolide A (15), which had two fewer chiral carbon centers at the C-11 and C-12 positions than (+)-calanolide A, had a comparably inhibitory activity and better therapeutic index (EC(50) = 0.11 mu M, TI = 818) against HIV-1 in vitro. A library based on its structural core was then designed and synthesized with introduction of nine diversity points in this article. The evaluations of anti-HIV-1 activity in vitro concluded their structure-activity relationships (SARs). A novel compound (10-bromomethyl-11-demethyl-12-oxo calanolide A, 123) was identified to have much higher inhibitory potency and therapeutic index (EC(50) = 2.85 nM, TI > 10,526) than those of the class compound against HIV-1. This finding provided a very important clue that modifications of the C ring at the C-10 position may be conducted to obtain drug candidates with better activity against HIV-1.
(+)-Calanolide A (1) 作为一种天然产物,先前被发现是HIV-1逆转录酶的抑制剂。在我们对其模板的进一步研究中,外消旋的11-去甲基-12-酮基calanolide A (15) 被发现。与(+)-calanolide A相比,它在C-11和C-12位上少两个手性碳中心,但其对HIV-1的抑制活性相当,并且具有更好的治疗指数(EC(50) = 0.11 μM,TI = 818)。随后,基于其结构核心设计并合成了一个化合物库,并在本文中引入了九个多样性点。体外评估抗HIV-1活性得出了它们的结构-活性关系(SARs)。发现了一个新的化合物(10-溴甲基-11-去甲基-12-酮基calanolide A,123),其对HIV-1的抑制效力和治疗指数(EC(50) = 2.85 nM,TI > 10,526)显著高于该类化合物。这一发现提供了非常重要的线索,即对C环的C-10位进行修饰,可能会得到对HIV-1活性更好的药物候选物。
Oxathioacetalization, thioacetalization and transthioacetalization of carbonyl compounds by N-bromosuccinimide: selectivity and scope
作者:Ahmed Kamal、Gagan Chouhan、Kaleem Ahmed
DOI:10.1016/s0040-4039(02)01610-6
日期:2002.9
Efficient oxathioacetalization, thioacetalization and transthioacetalization of carbonylcompounds have been achieved in high yields employing N-bromosuccinimide as a catalyst.