Abstract:Two optically active pseudo-hexopyranoses, pesudo-cl-Q--glucopyranose (1) and pseudo-B-&-altropyranose (11, were synthesized starting from &-araginose. converted to an acyclic aldehyde 2.dimethyl malonate under basic conditions provided a tetrahydroxylated cyclohexane-1,l-dicarboxylate 11 and a C-glycoside of B-L-arabinopyranose 12. From the compound 11, the desired two pseudo-sugars were synthesized by 1) thermal demethoxycarbonylation, 2 ) LiAl.H4 reduction, 3 ) hydroboration of the resulting I-hydroxymethyl… Show more
“…Cyclizations involving either intramolecular nucleophilic displacement or aldol condensations have been of particular value in the synthesis of carbahexopyranoses. In the course of their extensive work in this area, Suami, Tadano, and co-workers converted l -arabinose diethyl dithioacetal 943 to compound 944 by successive O -tritylation, O -benzylation, O -detritylation, and O -tosylation (Scheme ). , The parent aldehyde was regenerated from 944 with HgCl 2 and CaCO 3 , and substitution with sodium iodide gave the iodo compound 945 . Cyclization of 945 with dimethyl malonate and sodium hydride, followed by acetylation, provided cyclohexane derivative 946 and a secondary pyranose derivative 947 in the ratio of 1.3:1.…”
Section: 22 Synthesis From Carbohydrate Precursorsmentioning
confidence: 99%
“…Krapcho decarboxylation of 946 provided the cyclohexene derivative 948 , which gave compound 949 by lithium aluminum hydride reduction. Hydroboration−oxidation of 949 , followed by acetylation, deprotection, and final peracetylation, gave a mixture of 5a-carba-α- d -glucopyranose pentaacetate ( 922 ) and 5a-carba-β- l -altropyranose pentaacetate ( l - 586 ). , 146 Synthesis of 5a-Carba-α- d -glucopyranose Pentaacetate ( 922 ) and 5a-Carba-β- l -altropyranose Pentaacetate ( l - 586 ) a a Reagents: (i) TrCl, py, DMAP, 85%; (ii) HNa, BnBr; (iii) TsOH, MeOH, 79%, two steps; (iv) TsCl, py; (v) HgCl 2 , CaCO 3 ; (vi) NaI, acetone, reflux, 54% three steps; (vii) dimethyl malonate, NaH, DMF, then Ac 2 O, 76%; (viii) DMSO, NaCl, 170 °C, 75%; (ix) LAH, −15 °C, 83%; (x) B 2 H 6 , then H 2 O 2 , NaOH; (xi) Ac 2 O, py, 69% two steps; (xii) Na, liq NH 3 , then Ac 2 O, py, 49% 922 , 31% l - 586 . …”
Section: 22 Synthesis From Carbohydrate Precursorsmentioning
“…Cyclizations involving either intramolecular nucleophilic displacement or aldol condensations have been of particular value in the synthesis of carbahexopyranoses. In the course of their extensive work in this area, Suami, Tadano, and co-workers converted l -arabinose diethyl dithioacetal 943 to compound 944 by successive O -tritylation, O -benzylation, O -detritylation, and O -tosylation (Scheme ). , The parent aldehyde was regenerated from 944 with HgCl 2 and CaCO 3 , and substitution with sodium iodide gave the iodo compound 945 . Cyclization of 945 with dimethyl malonate and sodium hydride, followed by acetylation, provided cyclohexane derivative 946 and a secondary pyranose derivative 947 in the ratio of 1.3:1.…”
Section: 22 Synthesis From Carbohydrate Precursorsmentioning
confidence: 99%
“…Krapcho decarboxylation of 946 provided the cyclohexene derivative 948 , which gave compound 949 by lithium aluminum hydride reduction. Hydroboration−oxidation of 949 , followed by acetylation, deprotection, and final peracetylation, gave a mixture of 5a-carba-α- d -glucopyranose pentaacetate ( 922 ) and 5a-carba-β- l -altropyranose pentaacetate ( l - 586 ). , 146 Synthesis of 5a-Carba-α- d -glucopyranose Pentaacetate ( 922 ) and 5a-Carba-β- l -altropyranose Pentaacetate ( l - 586 ) a a Reagents: (i) TrCl, py, DMAP, 85%; (ii) HNa, BnBr; (iii) TsOH, MeOH, 79%, two steps; (iv) TsCl, py; (v) HgCl 2 , CaCO 3 ; (vi) NaI, acetone, reflux, 54% three steps; (vii) dimethyl malonate, NaH, DMF, then Ac 2 O, 76%; (viii) DMSO, NaCl, 170 °C, 75%; (ix) LAH, −15 °C, 83%; (x) B 2 H 6 , then H 2 O 2 , NaOH; (xi) Ac 2 O, py, 69% two steps; (xii) Na, liq NH 3 , then Ac 2 O, py, 49% 922 , 31% l - 586 . …”
Section: 22 Synthesis From Carbohydrate Precursorsmentioning
“…Later on, the same authors prepared (+)-methyl 3,4,5- O -tribenzyl-4- epi -shikimate from l -arabinose in a similar manner . In a modified procedure, the two C–C bond formation was achieved in a two-step protocol, which allowed also the synthesis of (−)-methyl 3,4,5- O -tribenzyl-5- epi -shikimate from d -ribose.…”
Shikimic acid is
a natural product of industrial importance utilized
as a precursor of the antiviral Tamiflu. It is nowadays produced in
multihundred ton amounts from the extraction of star anise (Illicium verum) or by fermentation processes. Apart from
the production of Tamiflu, shikimic acid has gathered particular notoriety
as its useful carbon backbone and inherent chirality provide extensive
use as a versatile chiral precursor in organic synthesis. This review
provides an overview of the main synthetic and microbial methods for
production of shikimic acid and highlights selected methods for isolation
from available plant sources. Furthermore, we have attempted to demonstrate
the synthetic utility of shikimic acid by covering the most important
synthetic modifications and related applications, namely, synthesis
of Tamiflu and derivatives, synthetic manipulations of the main functional
groups, and its use as biorenewable material and in total synthesis.
Given its rich chemistry and availability, shikimic acid is undoubtedly
a promising platform molecule for further exploration. Therefore,
in the end, we outline some challenges and promising future directions.
330ChemInform Abstract Starting with the trityl derivative (I) of L-arabinose, the iodide (IV) is prepared. It is cyclized with dimethyl malonate (V) and then acetylated, to yield the products (VII) and (VIII). (VII) is transformed into the allylic alcohol (IX) which is subjected to hydroboration and acetylation, producing the acetates (X) and (XI). These are deprotected to give the pseudo-α-D-glucopyranose (XIIb)and the pseudo-β-L-altropyranose (XIIIb) respectively.
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