Synthetic studies in steroidal sapogenins and alkaloids—V

Kessar, S. V.; Gupta, Y. P.; Mahajan, Raman; Joshi, Gaurav; Rampal, A.L.

doi:10.1016/0040-4020(68)88039-1

Cited by 18 publications

(12 citation statements)

References 13 publications

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“…!-pseuao-=og.r"61-6t h.rr" been prepared by this method, and the sy'nthesis of fl-Dl-pseudo-glucose (68) from acryIic acid (66) and furan (671 is shown in scheme L7. While the two synthetic methods described above have the disadvantage of Ieading to racemic products, opticatly pure cyclitols are available by synthesis from carbohydrates to which they are closely related' ft was suggested more than 90 years ago by Maguenne39 ah"t the biosynthesis of myo-inositol (9) involves the cyclisation of D-glucose (5), C-1 bonding to c-6, and this hypothesis has since been confirmed by a large experiments with biological systems, using biosynthetic cyclisation ptoceeds, as shown Likewise, the biosynthesis of (-)-shikimic acid (44) starts from 9glucose (6) and includes an oxidation-cyclisation-reduction sequence (Scheme Lg) ,44'45 b,rt in this case the carbon skeleton of glucose is rearranged prior Eo ring closure. In both biosyntheses the cyclising species is a 1,S-dicarbonyl compor:.nd and the cyclisation reaction is an enzyme catalysed j-ntramolecular aldol condensation.…”

Section: B Application Of the Diels-alder Reaclionmentioning

confidence: 93%

“…stlmulaLed rese,areh in the eyelitoL fleJ.d, but the availa.ble synt-het'ic me.hqds all, suffer from, a laclr, of readily accessible startlirg 38 rRaterilars -C;X'eIic monokebone.derivativ,e's, or iRoeoses, atse imqr.ortanL inteF[ediate,s irr cy,elitotr syntbesis andl biosyntllesi,s. The biesynthesers oF ggg-inositol (9)43 Elrd qf shikirrrr.ic acicl {p.I3)44'45 f".rn g-grucose (6), for exaq>len Broceed via. i.Ros,oses (see Scheues 18 and 19, F.ECI).…”

Section: \mentioning

confidence: 99%

“…It appears to be present' free or combined, in nearly all living cells. gy"-inositol is the parent sulcstance of many naturally occurring cyclitol derivatives and the raw material for the chemical synthesis of other cyclitols, and it was realised very early that it is configurationally related to D-glucose (6),39 the most abundant sugar (…”

Section: Introductionmentioning

confidence: 99%

“…The benzene extract was washed with water (3x 20 cm3), dried over sodium sulphate and evaporated to give tine chloyome?eury eontpound (129) as a foam (L.49 g, 75t), [o]D +53" (c 3, benzene) (Eoundz cl-, 4. '7i Hq 25-4. CzlHZtCLrqo, requires Cl, 5.0 i Hg, 28.2*li I" ,r.*-t. 6 2.88 (2 H, m, H-6,6'), 5.73 and 5.81 (2 H, 2 d', L2,3 = {3 ,4 = 4 Hz, H-2 and H-4) , 6-2L (I tt, t, H-3), 7.2-8.L (15 H, m, 3x OBz), 9.58 (1 H, s, H-l).…”

mentioning

confidence: 99%

“…); tH ,r.^.r. 6 Z':e (3 H, s, Ac)'' 6'90 and 7.02 (2 H, aa, %,69lr, H-5 and H-6), 7.79 (l H, s, H-3)' 7'3-8'3 (5 H, m, OBz), m7e 3tO (M', lot), 268 (M-CHrO; 38) r 163 (t'1-CHr0-PhCO; 21 , lO5 (Phco; lOO); 77 (Ce"S , 4').…”

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confidence: 99%

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Synthesis of Functionalised Cyclohexanes from Carbohydrates

Blattner¹

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<p>Beta-D-glucopyranose pentaacetate was photobrominated to give the 5-baromide from which 6-deoxy-Beta-D-xylo-hex-5-enopyranose tetraacetate was obtained by reductive elimination. This reaction sequence represents an efficient new route to the 5-ene. A detailed investigation into the photobromination of Beta-D-glucopyranose pentaacetate with bromine and with NBS led to the isolation of several by-products containing bromine substituents at C-1 and/or C-5; their reactions with zinc-acetic acid were studied, and the conformations. in solution of four alkenes derived from the 5-bromo compound were determined. 2,3,4-Triacylated 2,3,4,5-tetrahydroxycyclohexanones were Obtained by mercury (II) catalysed rearrangement of 5-deoxyhex-5-enopyranose esters. The mechanism of this rearrangement, and some enopyranose esters The mechanism of this rearrangement, reactions of the products were examined. The use of these new carbocyclic compounds in the synthesis of branched-chain cyclitol derivatives was explored. By means of diazomethane or, alternatively, hydrogen cyanide, substituted cyclohexanes with one-carbon branches and tertiary hydroxyl groups at the site of chain-branching were preared. Attempts to eliminate water from these tertiary alcohols to give substituted cyclohexene-carbonitriles or -carbaldehydes were unsuccessful.</p>

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Section: B Application Of the Diels-alder Reaclionmentioning

confidence: 93%

Section: \mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Synthesis of Functionalised Cyclohexanes from Carbohydrates

Blattner¹

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TheNef Reaction

Pinnick

1990

Organic Reactions

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The Nef reaction is usually defined as the conversion of a primary or secondary nitroalkane into the corresponding carbonyl compound. This reaction was reported by the Swiss chemist J. U. Nef in 1894. Hydrochloric and sulfuric acid give the same result. The conversion of a nitro group to a carbonyl group has become an important synthetic tool because of the ease of preparation of substituted nitro compounds by condensation of nitroalkanes with aldehydes (the Henry reaction), conjugate addition of nitroalkanes to electrophilic alkenes, or carbon alkylation of the dianion of primary nitroparaffins. The Nef reaction is one of the better examples of “umpolung” reactivity in which the original nitro compound anion functions as an acyl anion equivalent. This chapter discusses the Nef reaction and modifications of the original process that extend the variety of compounds which are useful as substrates. Each modification is considered according to general mechanistic type and is organized in a “reagent” approach. The Tabular Survey lists all known examples of both the Nef reaction and these modifications so that specific comparison of methods can be made.

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