Nucleophilic Aminoalkylation. Lithiated <i>N,N</i>‐Dimethylthiopivalamide

Seebàch, Dieter; Lubosch, Winfried

doi:10.1002/anie.197603132

Cited by 27 publications

(5 citation statements)

References 12 publications

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“…The reaction products then are at least 95% 8 and 16 and the reaction does not follow the path of Scheme II nor does 12 rearrange to 15. Accordingly the mechanism for the formation of the /3-diketones 5 and 7 from the thioesters 4 of limited synthetic value. Consideration of Scheme I suggests that if the reaction of 12 with thioester could be suppressed, that intermediate might be stable and trappable by subsequently added electrophiles.…”

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confidence: 99%

“…The organic phase was washed with saturated sodium bicarbonate, dried (MgS04), and concentrated. The product was purified by molecular distillation at 50 °C (0.01 mm) to give 620 mg (71%) of an epimeric mixture of 2-methyl-3-phenylthiirane: NMR (CDCI3) 1.22 (d, 1.05, J = 7 Hz, SCHCtfj), 1.65 (d, 1.95, J = 6 Hz, SCHC//3), 2.90-3.40 (m, 1, SC//CH3), 3.55 (d, 0.65, J = 6 Hz, SCtfPh), 4.13 (d, 0.35, J = 7 Hz, SCtfPh), 7.20-7.50 (m, 5, ArH); IR (neat) 3090,3070,3040,3010,2980,2940,2880,1605,1500,1455,1385,1350,1195,1095,1070,1030,1005,970,905,790,755,705 cm-'; mass spectrum (10 eV) m/e (rel intensity) 152 (4), 151 (17), 150 (100), 149 (42), 136 (7), 135 (67), 121 (5), 118 (22), 117 (29), 115 (8), 105 (9), 91 (14), 59 (17).…”

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Dipole-stabilized carbanions from thioesters. Evidence for stabilization by the carbonyl group

Reitz¹,

Beak²,

Farney³

et al. 1978

J. Am. Chem. Soc.

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confidence: 99%

Dipole-stabilized carbanions from thioesters. Evidence for stabilization by the carbonyl group

Reitz¹,

Beak²,

Farney³

et al. 1978

J. Am. Chem. Soc.

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“…Diese vor allem auch von den Arbeitsgruppen von Beak [ll] [12], Hoppe [13] und Meyers4) entwickelte Methode der Urnpolung [15] [16] hat sich als sehr nutzlich erwiesed). Sie ist auf Pivalthioamide [2], Pivalamide [3], Triphenylacetamide [4], 2,4,6-Triisopropyl-und 2,4,6-Tri-(tert -butyl)benzamide [ 51, 2,3-persubstituierte I) ' ) 3, 4, ' ) Teilweise in vorlaufigen Mitteilungen publiziert [I]. Succinimide [6], Phosphorsaureamide [7] [lo], ' Urethane' [8] [ 131 und Harnstoffe [9] angewendet worden.…”

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Tritylketone und Tritylenone. Beiträge zur sterisch erzwungenen Michael‐Addition und zur diastereoselektiven Aldol‐Addition

Seebàch¹,

Ertas

Locher

et al. 1985

Helvetica Chimica Acta

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Tritylketones are prepared from trityllithium and aldehydes, with subsequent CrO, oxidation (Scheme 1, 2a-f). Tritylenones are obtained from the saturated ketones and aldehydes or ketones, preferably by (CH3),Al-mediated aldol addition with subsequent dehydration (Scheme 2, products 2e, 4b-e). The carbonyl of the tritylketone group is sterically protected, but electronically effective (see A-C); thus, amine-free enolate solutions can be obtained directly with BuLi; also, exclusive conjugate addition of organolithium derivatives occurs with tritylenones (Srhemes 3-5, products Zd, 57, 15 examples). The lithiumenolates of tritylketones add to aldehydes with practically complete stereoselectivity (Scheme 6, products 10,9 examples): due to the bulkiness of the trityl group, only the (Z)-enolates 8 are formed, and the approach of the two trigonal centers in the aldol-addition step is enforced to occur with relative topicity ul. As a first example of an X-ray structure determination of a silyl enol ether, the crystal structure of (Z)-2-(trimethylsilyloxy)-l,l,l-triphenyl-2-butene (9) is reported. Fortunately, the blocking of the carbonyl group in trityl ketones can be run very specifically (without epimerization at the a-carbonyl center) by lithium triethylborohydride to furnish, after aqueous workup, primary alcohols and Ph3CH (Eqn. 4, products &20, 10 examples); the OH-group of the aldols 10 must be EE-, MOM-or MEM-protected (Scheme 8) before this C,C-bond cleavage can be conveyed. Some of the cleavage products are used for the chemical correlation of the aldol configuration and for the demonstration of the synthetic value of the presented method (see [21][22][23][24][25][26][27][28][29]

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“…This intermediate is probably stabilized by coordination of the carbanion lithium atom with the sulfur atom of the thioamide. There are precedents for deprotonation of N ‐Me groups of amides28,29 and some thioamides 30,31…”

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confidence: 99%

Atroposelectivity of Reactions of Benzylic Metalated Thiobenzamides and Thionaphthamides

2003

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N,N‐Dialkyl‐2‐methylbenzenecarbothioamides and naphthalenecarbothioamides were prepared by thionation of amides with Lawesson’s reagent under unusual conditions. Their axial chirality was evidenced. Benzylic deprotonation of thioamides bearing N,N‐diisopropyl groups with sec‐butyllithium was selective. The resulting anions were reacted with prochiral electrophiles (aromatic aldehydes, an unsaturated aldehyde or ketone, and an imine) to afford diastereomeric adducts (up to 88:12 dr). This is the first report on atroposelective C−C bond formation in the benzylic position of thioamides. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

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Nucleophilic Aminoalkylation. Lithiated N,N‐Dimethylthiopivalamide

Cited by 27 publications

References 12 publications

Dipole-stabilized carbanions from thioesters. Evidence for stabilization by the carbonyl group

Dipole-stabilized carbanions from thioesters. Evidence for stabilization by the carbonyl group

Tritylketone und Tritylenone. Beiträge zur sterisch erzwungenen Michael‐Addition und zur diastereoselektiven Aldol‐Addition

Atroposelectivity of Reactions of Benzylic Metalated Thiobenzamides and Thionaphthamides

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