Vitamin C and isovitamin C derived chemistry. 4. Synthesis of some novel furanone chirons

Abstract

The utility of the vitamin C and isovitamin C derived dibromo diacetates 3a,b for preparing synthetically useful chirons is further examined. Methodologies for transforming the readily accessible compounds 3a,b into 3,6-and 5,6-anhydrohexono-l,4-lactones lOa,b and 6a,b are presented. Elaboration of the lactone epoxides 6a-c has provided optically pure (S,S)-, meso-, and (R,R)-4,4'-bis-y-butyrolactones 18a-c. The difference in reactivity between some isomeric intermediates was related to the spatial arrangement a t the reactive sites. IntroductionUnequivocal stereocontrol constitutes the center piece of modern natural product synthesis. Most frequently the absolute configuration of the desired product has stemmed from the judiciously timed incorporation of chirally defined building blocks (chirons) during the synthesis and the subsequent configurational control of the asymmetric centers introduced. Carbohydrate-based schemes leading to a host of chirons have been especially rewarding in this respect; most of the desired routes have relied on the restructuring of furanoside and pyranoside systems.Our recent studies have demonstrated some relevant advantages of utilizing aldono-1,4-lactones, rather than the corresponding lactols, towards these ends. In practice aldono-1,4-lactones are highly crystalline, easily manipulated, and readily characterized substances. Large amounts of starting lactones may be prepared from inexpensive, commercially available materials. Publications from these laboratories have described the production of chirally defined butenolides 2 a -k '~~ from the ascorbic acids la,b and from ~-ribono-1,4-lactone. The preparation of three enantiomerically pure 4,5,6-trihydroxy-nor-~-leucines from la,b has also been r e p~r t e d .~

Deoxythiosugar Derivatives with Furano, Pyrano, and Septano Motifs from L‐Gulono‐1,4‐lactone and D‐Glycero‐D‐gulo‐heptono‐1,4‐lactone

“…2,6-Dibromo-2,6-dideoxy-L-idono-1,4-lactone (6): [10] A solution of l-gulono-1,4-lactone (5; 10 g, 0.056 mol) in HBr (33 % in glacial acetic acid; 56.2 mL) was stirred for 4.5 h at 30°C. After completion of reaction, methanol (150 mL) was added slowly, and the mixture was left overnight at room temperature.…”

A Cross‐Metathesis–Conjugate Addition Route to Enantiopure γ‐Butyrolactams and γ‐Lactones from a C2‐Symmetric Precursor

“…Using the standard conditions established previously along with benzylidene complex B as a catalyst, 57 % of 3c and 6 % of dimer 3d were isolated. C 2 -Symmetric bislactones were accessed by two different routes: through hydrogenation of 3c, followed by acid-catalyzed cleavage of the acetal to give bis-γ-butyrolactone 12, which was previously synthesized from ascorbic acid, [49] or through asymmetric dihydroxylation. [50] Very recently, a synthesis of 12 was described starting from the ethyl ester analogue of 3c, which was, in turn, synthesized from d-(-)tartrate by using an olefination reaction.…”

Synthesis of γ‐Lactones from Cycloocta‐1,5‐diene − Starting Materials for Natural‐Product Synthesis

“…Spectroscopic data have been reported previously. [27] [α] D 20 ϭ Ϫ78.5 (c ϭ 1.0, chloroform, ref. [27] [α] D 20 ϭ Ϫ81, c ϭ 0.99, chloroform), Ͼ98% ee (chiral GC, Beta-Dex TM 120 H 2 SO 4 and 77 mL of H 2 O) was added slowly.…”

“…[27] [α] D 20 ϭ Ϫ78.5 (c ϭ 1.0, chloroform, ref. [27] [α] D 20 ϭ Ϫ81, c ϭ 0.99, chloroform), Ͼ98% ee (chiral GC, Beta-Dex TM 120 H 2 SO 4 and 77 mL of H 2 O) was added slowly. The mixture was warmed up to room temperature and stirred for 1 h. Excess oxidant was destroyed with 2-propanol (5 mL) at 0°C.…”

“…Spectroscopic data agree with previously published ones. [27] A mixture of the cis-and trans-isomers of 5Ј-hydroxytetrahydro-2,2Ј-bifuranyl-5-one (26) was identified as a side product of this reaction in 2Ϫ25% yield (GC). 1 According to known procedures for the corresponding racemic compounds [13] a 74:26 mixture of acetates (1S,2S,5R,6R)-(ϩ)-4 (Ͼ98% ee) and (1R,2R,5R,6R)-(ϩ)-5 (80% ee) (1.50 g, 7.5 mmol) [15] was dissolved in acetone (150 mL).…”