Anthracyclinones. Part 3. Use of di-isopropylidene-D-glucose and a modified marschalk reaction to introduce a tertiary carbinol function into ring D of anthracyclinones

Qureshi, Shireen; Shaw, G.

doi:10.1039/p19850000875

Cited by 10 publications

(3 citation statements)

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“…Prior to generation of the indolizidine aldehyde 55 was converted into the corresponding terminal alkyne 57 in 73% yield using dimethyl (1-diazo-2-oxopropyl)phosphonate 56 . After some exploration of debenzylation conditions, the free alcohol intermediate 58 was obtained from 57 using boron trichloride. A Mitsunobu reaction transformed this intermediate to the intended indolizidine (±) - 8 - epi - 219F in 70% yield.…”

Section: Resultsmentioning

confidence: 99%

Organometallic Enantiomeric Scaffolding: A Strategy for the Enantiocontrolled Construction of Regio- and Stereodivergent Trisubstituted Piperidines from a Common Precursor

2011

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Reported herein is a general and efficient method to construct 2,3,6-trisubstituted piperidines in a substituent-independent fashion. From the high enantiopurity organometallic scaffold (−)-Tp(CO)2[(η-2,3,4)-(1S, 2S)-1-benzyloxycarbonyl-5-oxo-5,6-dihydro-2H-pyridin-2-yl)molybdenum (Tp = hydridotrispyrazolylborato), a variety of TpMo(CO)2-based 2,3,6-trifunctionalized complexes of the (η-3,4,5-dihydropyridinyl) ligand were easily obtained in 5 steps through a sequence of highly regio- and stereospecific metal-influenced transformations (15 examples). From the 2,3,6-trifunctionalized molybdenum complexes, either 2,6-cis-3-trans or 2,3,6-cis systems were selectively obtained through the choice of an appropriate stereodivergent demetalation protocol. The potential of this strategy in synthetic chemistry was demonstrated by the short total synthesis of four natural and one non-natural alkaloids: indolizidines (±)-209I and (±)-8-epi-219F in the racemic series, and enantiocontrolled syntheses of (−)-indolizidine 251N, (−)-quinolizidine 251AA, and (−)-dehydroindolizidine 233E.

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Section: Resultsmentioning

confidence: 99%

Organometallic Enantiomeric Scaffolding: A Strategy for the Enantiocontrolled Construction of Regio- and Stereodivergent Trisubstituted Piperidines from a Common Precursor

2011

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“…Subsequent cleavage of the chiral auxiliary in 8 with NaBH 4 provided the diol 9 in 82% yield. The primary alcohol was selectively protected as the pivaloyl ester, and the benzyl ether was cleaved using BCl 3 ·Me 2 S without affecting the pendant olefin. The resulting diol was subsequently protected using TESOTf and 2,6-lutidine to give the silyl ether 10 (74% overall yield).…”

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confidence: 99%

Total Synthesis of Incednam, the Aglycon of Incednine

et al. 2010

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The first total synthesis of incednam (1), the aglycon of antibiotic incednine (2), is described. Incednine has been reported to exhibit significant inhibitory activity against the antiapoptotic oncoproteins Bcl-2 and Bcl-xL. The synthesis of 1 commenced with the preparation of the C1-C13 subunit 3 and the C14-C23 subunit 4. The construction of the novel 24-membered macrocycle was achieved by the application of a Stille coupling between 3 and 4, followed by macrolactamization.

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“…Dibromo 6 was also derived from 7 ( 3 without its 5,6-isopropylidene group) in 74% yield with 2.2 equiv of NBS. Compound 7 , mp 97−98 °C, was prepared from 3 by acetic acid treatment in 94% yield . In addition to a peak at m / z 229 (M + − 15), the mass spectrum of 7 displayed a major peak at 98 corresponding to losses of 116 and 30.…”

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confidence: 99%