Biogenetic-type synthesis of polyketides Part IX

Scott, A.L.; Guilford, H.; Skingle, DC

doi:10.1016/s0040-4020(01)98097-4

Cited by 11 publications

(2 citation statements)

References 12 publications

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“…Compound 1 (commercially available) was prepared (75%) as described 64 but using EtOH instead of EtOAc to obtain a higher solubility. Compounds 2 4b , 5 4b and 13 4a were previously prepared.…”

Section: Methodsmentioning

confidence: 99%

Highly Diastereoselective Hydrogenations Leading to β-Hydroxy δ-Lactones in Hydroxy-Protected Form. A Modified View of δ-Lactone Conformations

et al. 2003

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Enol MEM ethers 4 and 15 and the corresponding enol acetates were hydrogenated over Pd/C with very high (>99%) diastereoselectivity to saturated delta-lactones. A stereochemical generalization can be formulated thus: trans-5,6-disubstituted 1-oxa-3-cyclohexen-2-ones (e.g. 14 and 15) are hydrogenated over Pd with high selectivity from the side trans to the C(6)-substituent. A mechanistic rationalization of the stereochemical outcome in the Pd-catalyzed hydrogenation of this as well as other types of substituted alpha,beta-unsaturated delta-lactones is presented. An analysis of X-ray crystallographic data for 67 compounds demonstrated a great conformational diversity of the saturated delta-lactone ring. Besides, ab initio calculations (HF/6-31G) indicated a very high conformational mobility. Thus, the lowest calculated transition state for the conversion of the half-chair, most stable, conformer of delta-valerolactone to the boat-type conformer lies only 1.93 kcal/mol above the former. Beside these two conformers, also chair, envelope and skew conformations are accessible; all lie less than 2 kcal/mol above the half-chair. The previous conformational paradigm comprising only boat and half-chair types is incomplete.

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Section: Methodsmentioning

confidence: 99%

Highly Diastereoselective Hydrogenations Leading to β-Hydroxy δ-Lactones in Hydroxy-Protected Form. A Modified View of δ-Lactone Conformations

et al. 2003

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“…Syntheses of 11- 4,10, [1,5] benzodiazepin-1-ones KEIZO MATSUO,* IKUKO TANI, and KUNIYOSHI TANAKA Faculty of Pharmaceutical Sciences, Kinki University, 3-4-1 Kowakae, Higashiosaka, Osaka 577, Japan (Received July 22, 1987) 11-Substituted 3-methyl-3, 4, 10,1 1 -tetrahydro-1 H, 5H-pyrano [4 ,3-b] hydroxy-5-methyl-2-penten- 5-olide In the course of our synthetic studies on biologically active compounds using dimedone, tetronic acids, and tetramic acids,1) we reported that some 10-substituted 3,3-dimethyl-3, 4, 9, 10-tetrahydro-1H-furo-and -pyrrolo [4, 3-b] [1, 5] benzodiazepin-1-ones (1 and 2) showed analgesic activity as strong as that of aminopyrine in the phenylquinone writhing test in mice.2) Namely, the extents of inhibition were 56.1% with la, 61.0% with lb, and 68.3% with 2 at the dose of 50 mg/kg p.o., while that of aminopyrine was 66.2%. The above observations prompted us to synthesize benzodiazepinone derivatives fused with other heterocyclic compounds in order to test their analgesic activity.…”

mentioning

confidence: 99%

Syntheses of 11-substituted 3-methyl-3,4,10,11-tetrahydro-1H,5H-pyrano(4,3-b)(1,5)benzodiazepin-1-ones.

Matsuo

Tani

Tanaka

1987

CHEMICAL & PHARMACEUTICAL BULLETIN

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Construction of Highly Substituted Nitroaromatic Systems by Cyclocondensation. Part II. Conversion of 4‐nitro‐3‐oxobutyrate to 3‐nitrosalicylates

Duthaler

1983

Helvetica Chimica Acta

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The base-catalyzed reaction of 4-nitro-3-oxobutyrate (6) with acetylacetone (8, Scheme 3), formylacetone (13, Scheme 4), formylcyclohexanone (31, Scheme 5), 2,4-dioxopentanoates 39 and 40 (Scheme 6), and 2,4,6-heptanetrione (2, Scheme 7) affords substituted 3-nitrosalicylates, products of a double aldol condensation. With unsymmetrical dicarbonyl compounds both regioisomers are formed. High selectivity was found in the case of P-keto-aldehydes 13 and 31 with preferred addition of the NO,-substituted carbon to the aldehyde carbonyl. The major products of these cyclocondensations, which are isolated in yields ranging from 20% to SO%, are all new compounds. Less successful are the conversions with b-alkoxy-and P-chloro-vinyl ketones (23, 25, and 26), and with alkinone 24, where the condensation products are formed in very low yield (Scheme 4 ) .Dicyclohexyl-18-crown-6 (0.25 equiv.). d, See [I]. ') 1,8-Diazabicyclo[5.4.0]undec-7-ene. ' )Without molecular sieves.

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Biogenetic-type synthesis of polyketides Part IX

Cited by 11 publications

References 12 publications

Highly Diastereoselective Hydrogenations Leading to β-Hydroxy δ-Lactones in Hydroxy-Protected Form. A Modified View of δ-Lactone Conformations

Highly Diastereoselective Hydrogenations Leading to β-Hydroxy δ-Lactones in Hydroxy-Protected Form. A Modified View of δ-Lactone Conformations

Syntheses of 11-substituted 3-methyl-3,4,10,11-tetrahydro-1H,5H-pyrano(4,3-b)(1,5)benzodiazepin-1-ones.

Construction of Highly Substituted Nitroaromatic Systems by Cyclocondensation. Part II. Conversion of 4‐nitro‐3‐oxobutyrate to 3‐nitrosalicylates

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