Asymmetric reductions of propargyl ketones

Midland, M. Mark; Tramontano, Alfonso; Kazubski, Aleksander; Graham, Richard S.; Tsai, David J. S.; cardin, Daniel B.

doi:10.1016/s0040-4020(01)82422-4

Cited by 129 publications

(47 citation statements)

References 59 publications

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“…Oxidation of 3/4 (1 : 1) with periodinane yielded 93% of a single ketone 5, establishing that 3 and 4 are diastereoisomers. This ketone could not be reduced with a sufficiently high degree of diastereoselectivity (< 2 : 1) by either NaBH 4 , Alpine Borane [24], or BH 3 in the presence of Coreys oxazaborolidine [25]. Addition of Et 3 SiCCMgBr to 2 yielded 80% of a 1 : 2 mixture 6/7.…”

Section: Synthesis Of Uridine-derived Monomers and Dimersmentioning

confidence: 99%

Oligonucleosides with a Nucleobase-Including Backbone, Part 1, Concept, Force-Field Calculations, and Synthesis of Uridine-Derived Monomers and Dimers

Eppacher¹,

Solladié²,

Bernet³

et al. 2000

HCA

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A new type of oligonucleosides has been devised to investigate the potential of oligonucleosides with a nucleobase-including backbone to form homo-and/or heteroduplexes (cf. Fig. 2). It is characterised by ethynyllinkages between C(5') and C(6) of uridine, and between C(5') and C(8) of adenosine. Force-field calculations and Maruzen model studies suggest that such oligonucleosides form autonomous pairing systems and hybridize with RNA. We describe the syntheses of uridine-derived monomers, suitable for the construction of oligomers, and of a dimer. Treatment of uridine-5'-carbaldehyde (2) with triethylsilyl acetylide gave the diastereoisomeric propargylic alcohols 6 and 7 (1 : 2, 80%; Scheme 1). Their configuration at C(5') was determined on the basis of NOE experiments and X-ray crystal-structure analysis. Iodination at C(6) of the (R)-configured alcohol 7 by treatment with lithium diisopropylamide (LDA) and N-iodosuccinimide (NIS) gave the iodide 17 (62%), which was silylated at OÀC(5') to yield 18 (89%; Scheme 2).

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Section: Synthesis Of Uridine-derived Monomers and Dimersmentioning

confidence: 99%

Oligonucleosides with a Nucleobase-Including Backbone, Part 1, Concept, Force-Field Calculations, and Synthesis of Uridine-Derived Monomers and Dimers

Eppacher¹,

Solladié²,

Bernet³

et al. 2000

HCA

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“…Interestingly, the reactivity of highly activated tertiary alkynols such as 1h is complicated by the competing MeyerSchuster rearrangement [11] and isolation of ether 2w required strict control of the temperature (RT), the reaction time (30 min), and neutralization prior to the purification step (Entry 23). [12] Moreover, when the starting material was enantiomerically enriched propargylic alcohol 1a (94 % ee) [13] the corresponding ethyl ether 2a was obtained in a racemic form. All these results seem to indicate that the reaction proceeds through the formation of a stabilized carbonium intermediate.…”

Section: Resultsmentioning

confidence: 99%

Metal‐Free Catalytic Nucleophilic Substitution of Propargylic Alcohols

et al. 2006

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Organic acids such as PTS efficiently catalyze direct nucleophilic substitutions of the hydroxy groups of propargylic alcohols with a large variety of carbon‐ and heteroatom‐centered nucleophiles. Reactions can be conducted under mild conditions and in air without the need for dried solvents. Reactions on multigram scales are also possible. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

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“…Compound I is characterized by a pleasant and sweet light coconut odor [4] and is used as aromatizer in perfumery and in the manufacture of alcoholic drinks and tinctures [5]. (-)-(R)-Massoia lactone is also an alarm pheromone in two formicine species of the family Camponotus [6,7]. Synthetic massoia lactone [8] is widely used in perfume and food industries instead of the natural compound with a view to save its natural sources.…”

mentioning

confidence: 99%

“…A number of procedures have been reported for the preparation of both natural (-)-(R)- [1,[3][4][5][6][7][8][9][10][11][21][22][23][24][25][26][27][28][29][30] and synthetic (+)-(S)-massoia lactone [1, 21, 23-25, 28, 31], but the use of these procedures is restricted because of expensive reagents [7,14,26], low selectivity [6,10,11,22,25], enzymatic transformations [1,9,16,24], and large number of steps [3,27,29]. The present article describes a stereoselective synthesis of (-)-(6R)-massoia lactone with the use of methyl 3-[(tributylstannyl)methyl]but-3-enoate (V) as C 5 -allylic building block, which is available from ethyl 3,3-diethoxypropionate (VI) in five preparative steps (Scheme 1) [32,33].…”

mentioning

confidence: 99%