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11.
Chonticha Masusai Darunee Soorukram Chutima Kuhakarn Patoomratana Tuchinda Chaveng Pakawatchai Vichai Reutrakul Manat Pohmakotr 《Helvetica chimica acta》2012,95(10):1912-1927
The Morita? Baylis? Hillman (MBH) reactions of (4S,5R,7R,8R)‐ and (4R,5R,7R,8R)‐4‐hydroxy‐7,8‐dimethoxy‐7,8‐dimethyl‐6,9‐dioxaspiro[4.5]dec‐2‐en‐1‐ones ( 2 and 3 , resp.) with aldehydes using various catalysts were studied. A combination of Bu3P/phenol in THF was found being optimum conditions giving the corresponding MBH adducts with high diastereoisomeric ratios. After separation, each stereomerically pure isomer of the MBH adducts was subjected to hydrolysis employing 1% aq. CF3COOH (TFA) in a water bath of an ultrasonic cleaner to afford the corresponding polyhydroxylated cyclopentenones in good yields. 相似文献
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Manat Pohmakotr 《Tetrahedron》2007,63(8):1806-1820
A general method for the preparation of 5-alkylidene-2-cyclopentenones and their 2-phenylsulfanyl substituted derivatives, involving the intramolecular acylation of α-sulfinyl carbanions with cyclopentadiene-α,β-unsaturated esters as the key reaction followed by flash vacuum pyrolysis, is described. The reactions start from readily available Diels-Alder adducts, synthons of α-carbanions of α,β-unsaturated esters. 相似文献
13.
Manat Pohmakotr 《Tetrahedron》2007,63(20):4328-4337
The reaction of the (bis)trimethylsilyloxy derivative of diethyl succinate with imines in the presence of ZnCl2 provides a general stereoselective entry to β-carboethoxy-γ-lactams. 相似文献
14.
Tassaporn Sawangphon Praewpan Katrun Korbua Chaisiwamongkhol Manat Pohmakotr Vichai Reutrakul Thaworn Jaipetch 《合成通讯》2013,43(12):1692-1707
An improved one-pot method to synthesize vinyl sulfones from unsaturated systems by using molecular iodine/sodium arenesulfinate/sodium acetate as reagents was described. Vinyl sulfones derived from styrene derivatives were generally obtained in good to excellent yields except for those bearing strong electron releasing substituent. Aliphatic alkenes and activated alkenes gave the corresponding vinyl sulfone products in moderate to good yields. Arylacetylenes yielded the respective β-iodovinyl sulfones in good yields while low yield was observed with aliphatic terminal alkyne. The potentials of the method entail simplicity, short reaction time, non-anhydrous reaction conditions, employing inexpensive, non-metallic reagent and integrating two reactions that are commonly accomplished separately into a single operation. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file. 相似文献
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Manat Pohmakotr Darunee Soorukram Patoomratana Tuchinda Samran Prabpai Palangpon Kongsaeree Vichai Reutrakul 《Tetrahedron letters》2004,45(22):4315-4318
The vicinal dianions derived from chiral succinic acid derivatives, 1,4-bis[(4R,5S)-3,4-dimethyl-2-oxo-5-phenylimidazolidin-1-yl]butane-1,4-dione and 1,4-bis[(4S,5R)-3,4-dimethyl-2-oxo-5-phenylimidazolidin-1-yl]butane-1,4-dione react with arylmethyl bromides with high diastereo- and regio-selectivity to provide the corresponding chiral α-arylmethylated succinic acid derivatives; the (R)-products are converted into (R)-β-arylmethyl-γ-butyrolactones and (R)-α-arylmethyl-γ-butyrolactones. 相似文献
17.
Pramchai Deelertpaiboon Suwatchai Jarussophon Patoomratana Tuchinda Chutima Kuhakarn Manat Pohmakotr 《Tetrahedron letters》2009,50(46):6233-6235
Treatment of glycals with trialkylaluminum in the presence of a catalytic amount of Yb(OTf)3 leads to the corresponding alkyl 2,3-unsaturated glycosides in good to excellent yields. Reactions of protected glycals are achieved under very mild conditions. 相似文献
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A sufficient condition is given under which an infinite computable family of Σ-1
a
-sets has computable positive but undecidable numberings, where a is a notation for a nonzero computable ordinal. This extends a theorem proved for finite levels of the Ershov hierarchy in
[1]. As a consequence, it is stated that the family of all Σ-1
a
-sets has a computable positive undecidable numbering. In addition, for every ordinal notation a > 1, an infinite family of Σ-1
a
-sets is constructed which possesses a computable positive numbering but has no computable Friedberg numberings. This answers
the question of whether such families exist at any—finite or infinite—level of the Ershov hierarchy, which was originally
raised by Badaev and Goncharov only for the finite levels bigger than 1. 相似文献
20.
Chutima Kuhakarn Krisada Kittigowittana Pattama Ghabkham Manat Pohmakotr Vichai Reutrakul 《合成通讯》2013,43(19):2887-2892
A mild oxidation of alcohols to the respective carbonyl compounds with o‐iodoxybenzoic acid (IBX) catalyzed by n‐Bu4NBr in a water/dichloromethane (1:1) mixture is described. The method offers the advantage of a simple, inexpensive catalyst and the diminution of organic solvent employed in the reaction. 相似文献