Furanoid Glycals Research Articles

Fujiwara‐Moritani Assisted Synthesis of Conjugated 2,3‐Dihydrofuran Trienes and Corresponding 2,3‐Dihydrobenzofuran Derivative

AbstractPalladium catalysed C−H activation has been carried out on furanoid glycals to afford highly substituted and conjugated 2,3‐dihydrofuran trienes and then its conversion into highly substituted 2,3‐dihydrobenzofuran was achieved starting from commercially available, inexpensive sugar precursor diacetone‐D‐glucose. Claisen‐Schmidt condensation reaction, Fujiwara‐Moritani cross coupling reaction and 6π electro‐cyclisation reaction were utilized as the key steps in this synthetic route. Diacetone‐D‐glucose was converted into dihydrofuran moiety via Claisen Schmidt condensation which was submitted to Fujiwara‐Moritani C−C coupling reaction to afford 2,3‐O‐isopropylidine‐4,5‐disubstituted 2,3‐dihydrofurans. Excellent yields (up to 97 %) were obtained during C−C coupling step which indeed is an accomplishment. Next, two step chemical route was established for conversion of these substituted and conjugated 2,3‐dihydrofuran triene moieties into corresponding substituted 2,3‐dihydrobenzofuran moiety.

Discovery and Development of an Unusual Organocatalyst for the Conversion of Thymidine to Furanoid Glycal

Discovery and Development of an Unusual Organocatalyst for the Conversion of Thymidine to Furanoid Glycal

Organocatalytic Conversion of Nucleosides to Furanoid Glycals.

A class of organocatalysts that are highly active for the conversion of 2'-deoxynucleosides to furanoid glycals have been discovered. These phosphorimides, (Ph2PS)2NH and (Ph2PSe)2NH, were shown to effectively mediate persilylation of 2'-deoxynucleosides allowing the elimination of the nucleobase giving the corresponding glycal. These mild conditions were demonstrated in the syntheses of glycals with various substitution patterns while minimizing the formation of undesired byproducts and expanding the scope of this methodology.

The evolution of comprehensive strategies for furanoid glycal synthesis and their applications

Cyclic enol ether frameworks, especially stereochemically pure furanoid and pyranoid glycals are well known highly functionalized chiral building blocks.

Modified Synthesis of 3′-OTBDPS-Protected Furanoid Glycal

Thermolytic cleavage of 3′-OH protected thymidine is the most common method of preparing furanoid glycals. We have observed that glycosidic bond cleavage is more facile when the 5′-OH of thymidine was also protected with a silyl group. Addition of trimethylsilyl chloride facilitated cleavage of the glycosidic bond; thus, both modifications are required for the formation of the furanoid glycal. Investigations into the selective deprotection of 5′-silyl versus 3′-silyl and subsequent glycosidic bond cleavage are reported herein.

Stereoselective synthesis of 2′-deoxynucleoside analogues as building blocks for deoxynucleoside chemistry

Three pairs of enantiomeric 2′-deoxynucleoside analogues 4a, 4b, 4c, 4e and 4d, 4f, respectively, have been synthesized from enantiomerically pure highly functionalized furanoid glycals 2a– d by involving a similar synthetic strategy. These analogues have various well defined stereogenic centres and are useful building blocks for deoxynucleoside chemistry.

Stereoselective total syntheses of (+)- exo- and (−)- exo-brevicomins, (+)- endo- and (−)- endo-brevicomins, (+)- and (−)-cardiobutanolides, (+)-goniofufurone

Stereoselective total syntheses of aggregation pheromones (+)- exo-brevicomin ( 9a), (−)- exo-brevicomin ( 9b), (+)- endo-brevicomin ( 9c), (−)- endo-brevicomin ( 9d) and styryllactones (+)-cardiobutanolide ( 14a), (−)-cardiobutanolide ( 14b), and (+)-goniofufurone ( 19a) were achieved in good yields from enantiomerically pure highly functionalized furanoid glycal building blocks ( 1a– d) involving similar synthetic strategies, thus making these furanoid glycals highly useful building blocks in diversity-oriented synthesis (DOS).

ChemInform Abstract: The Reactivity of Furanoid and Pyranoid Glycals Towards Aromatic Grignard Reagents and a Nickel Catalyst.

Abstract By reaction with aromatic Grignard reagents in the presence of low valent nickel species at low temperature, the 1,2-unsaturated furanoid glycal ( 1 ) undergoes coupling reaction to produce 2,3-unsaturated products ( 1a,b ) as pure stereoisomers. When these reaction conditions are applied to protected 1,2-unsaturated pyranoid glycals ( 2, 3, 4 ), both cross-coupling and elimination reactions occur to give conjugated diene-alcohol derivatives ( 2a; 3a,b; 4a,b , respectively), in moderate yield.

Synthesis of Enantiomerically Pure Highly Functionalized Furanoid Glycal and 2,5‐Dihydrofuran Building Blocks

AbstractDifferently protected enantiomerically pure furanoid glycals (5a–d) and highly functionalized 2,5‐dihydrofurans (6a–b) were synthesized from their respective 2,3,4‐trisubstituted tetrahydrofurans. These furanoid glycals were identified as1,4‐anhydro‐2‐deoxy‐5,6‐O‐isopropylidene‐3‐O‐benzyl‐L‐arabino‐hex‐1‐enitol, 1,4‐anhydro‐2‐deoxy‐5,6‐O‐isopropylidene‐3‐O‐benzyl‐L‐ribo‐hex‐1‐enitol, 1,4‐anhydro‐2‐deoxy‐5,6‐O‐isopropylidene‐3‐O‐benzyl‐D‐ribo‐hex‐1‐enitol and 1,4‐anhydro‐2‐deoxy‐5,6‐O‐isopropylidene‐3‐O‐benzyl‐D‐arabino‐hex‐1‐enitol, respectively. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

ChemInform Abstract: Synthesis of Pyranoid and Furanoid Glycals from Glycosyl Sulfoxides by Treatment with Organolithium Reagents.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis of Pyranoid and Furanoid Glycals from Glycosyl Sulfoxides by Treatment with Organolithium Reagents

AbstractGlycosyl sulfoxides can be conveniently transformed into pyranoid or furanoid glycals by treatment with organolithium reagents. The more likely reaction pathway involves a sulfoxide/metal exchange reaction to generate a glycosyllithium derivative that undergoes β‐elimination of its C‐2 substituent. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Coumarin base-pair replacement as a fluorescent probe of ultrafast DNA dynamics

The design and synthesis of a novel coumarin C-riboside are described, and is based on the well-known photoprobe Coumarin 102. A diastereofacial selective Heck coupling between a furanoid glycal and a coumarin triflate provided a method for glycoside formation. The coumarin C-glycoside was incorporated synthetically into DNA oligomers, and was used to probe ultrafast dynamics of duplex DNA using time-resolved Stokes shift methods.

Synthesis of D-D4FC, a biologically active nucleoside via an unprecedented palladium mediated Ferrier rearrangement-type glycosidation with an aromatization prone xylo-furanoid glycal

D-D4FC ( 1 ) is an anti-HIV agent currently under phase II clinical trial (Pharmaset Inc). Its molecular architecture is suitable for a Ferrier rearrangement kind of operation on a furanoid glycal to fix the position of the double bond and the relative stereochemistry. Despite the fact that classical Ferrier rearrangement does not work on furanoid glycals, a palladium mediated modified protocol has been developed for the glycosidation of an aromatization prone xylo-furanoid glycal ( 5 ) for the synthesis of D-D4FC.

Synthesis of a New Furanoid Glycal Auxiliary

A route is investigated for the synthesis of 3-O-allyl-1,4-anhydro-5-O-tert-butyldiphenylsilyl-2-deoxy-D-erythro-pent-1-enitol. The highest overall yield was obtained when 5′-O-(tert-butyldiphenylsilyl)thymidine was converted to the corresponding furanoid glycal and subsequently 3-O-allylated.

From a glycal to a [1,3]dioxolan-4-yl ester

1,2:5,6-di- O-Isopropylidene-α- d-glucofuranose can be used as a starting material for the stereoselective synthesis of a novel [1,3]dioxolan-4-yl ester by an acid catalyzed rearrangement reaction of an unusual furanoid glycal.

A Short, Efficient Synthesis of 2′‐Deoxypseudoisocytidine Based on Heck‐Chemistry.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A Short, Efficient Synthesis of 2′-Deoxypseudoisocytidine Based on Heck-Chemistry

A novel synthesis of 2′-deoxypseudoisocytidine as well as of its phosphoramidite building block for oligonucleotide synthesis is presented. The synthesis is based on Heck-coupling between N-protected pseudoisocytosine and a silyl protected furanoid glycal. With this procedure the corresponding phosphoramidite building block is obtained in 5 steps and an overall yield of 28%.

Synthesis of 1,4‐Anhydro‐2‐deoxy‐D‐ribitol Derivatives from Thymidine Using Improved Preparation of Furanoid Glycals.

AbstractFor Abstract see ChemInform Abstract in Full Text.

ChemInform Abstract: Synthesis of erythro and threo Furanoid Glycals from 1‐ and 2‐Phenylselenenyl‐carbohydrate Derivatives.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ヌクレオシドのリチウム化反応における新展開 ケイ素およびスズ官能基の転位

Described herein are three types of anionic migration of silyl and stannyl groups observed during the lithiation (hydrogen-lithium exchange) of nucleosides. In the first example of 9- [2, 3, 5-tris-O- (tert-butyldimethylsilyl) -β-D-ribofuranosyl]-6-chloropurine, the 8-trimethylsilyl or 8-tributylstannyl group introduced by lithiation underwent migration to the 2-position (migration within the base) through further lithiation of the less acidic H-2. The second example was observed by using 1- (2-deoxy-D-erythro-pent-1-enofuranosyl) uracil as a substrate, wherein the lithiationbased migration took place from the 6-position of the nucleobase to the 2'-position of the sugar (furanoid glycal). The last example came from the lithiation of the 5'-O-silylated or -stannylated anti-HIV agent d 4 T (2', 3'-didehydro-3'-deoxythymidine). As a result of highly unusual vinylic lithiation in the presence of allylic hydrogen, these 5'-O-protecting groups were transferred to the 3'-position of the unsaturated sugar (migration within the sugar). Since stannyl group can be transformed in various ways, the above three examples have opened up access to nucleoside derivatives that have been difficult to be synthesized by other methods.