Sugar olefins

TiPSON - COHEN Oleflnatlon Conversion o( sugar glycols via epoxides into sugar olefins. 

In 2008, Chakraborty el al. reported that Michael addition of nitromethane to the sugar olefinic derivative 36 provided the sugar-based (I-nitro acid ester 37 (Scheme 14), which was used as starting material for the preparation of a novel type of cyclohexyl amines.36... 

Synthesis of p-lactam antibiotics from sugars (either as chiral auxiliary or chiron), describing the general methodology developed in 1990s by Chmielewski and based on [2 + 2] cycloaddition of isothiocyanides to sugar olefins, was also comprehensively reviewed.5... 

The 1,3-dipolar cycloaddition between the sugar nitrone and sugar olefins was proposed54 and an example is shown in Fig. 39.54e... 

The CM of fatty acids and derived compounds also has been used for the production of fine chemicals that are difficult to obtain by other synthetic approaches. Some examples include the synthesis of a plant growth stimulant, an insect pheromone precursor, the sex pheromone of the peach twig borer moth, and others [28]. Furthermore, the conjugation of fatty acid derivatives, sugars, and amino acids via CM was shown by Vemall and Abell [41]. C4 with a catalyst loading of 20 mol% was used to perform the CM of either Ai-Boc-L-ly sine or N-Boc-L-cysteine bearing a 10-undecenoic chain with methyl 10-undecenoate or a sugar olefin. 

The stereochemical course of the reduction of sugar olefins is primarily governed by the neighboring groups. This step proved to be highly stereoselective in the pyranose series, as shown in the synthesis of the thromboxane B2 by Hanessian [106]. As shown in Scheme 11.33, ketone 127,... 

Base-catalyzed isomerization of epoxides into allylic alcohols is a method of choice for the preparation of unsaturated sugars olefin 10 was prepared by treatment of oxirane 9 with a strong base. This process is similar to the Horwitz s)uithesis of d4T presented in Scheme 7. The Tipson-Cohen methodology is frequently applied for the synthesis of 2,3-unsaturated sugars as shown in Scheme 10 such reduction might be performed also under microwave irradiation [6]. 

Entry Sugar Olefin Conditions Products R Yield (a// ) Bet. 

Entry Sugar Olefin Lewis Acid Product Yield... 

TIpsoN - COHEN Ofeflnatlon Conversion of sugar glycols v a epoxides into sugar olefins. 

The steric course of the osmylation of five higher sugar olefins, such as compounds 44 has been examined. Kishi s rule was I ound to be obeyed in all but one case (44, X,Y = O). ... 

Disulfonate esters of vicinal diols sometimes undergo reductive elimination on treatment with sodium iodide in acetone at elevated temperature and pressure (usually l(X)-200°). This reaction derived from sugar chemistry has been used occasionally with steroids, principally in the elimination of 2,3-dihy-droxysapogenin mesylates. The stereochemistry of the substituents and ring junction is important, as illustrated in the formation of the A -olefins (133) and (134). 

Decomposition by cyanide gives the same products (except that the sugar forms the cyanhydrin) and probably involves coordination of cyanide in the trans position, followed by the elimination of Co(III) and oxygen (as RO ) to give the olefin. For further references and discussion about both these reactions see Chapter 13 of ref. (136). These two methods of decomposition... 

C. Miscellaneous.—Among ylides, PhsP CHR, used in conventional olefin synthesis with protected keto-sugars are those with R = H, CN, SMe, and COR. ... 

The asymmetric Baylis-Hillman reaction of sugar-derived aldehydes as chiral electrophiles with an activated olefin in dioxane water (1 1) proceeded with 36-86% de and in good yields of the corresponding glycosides (Eq. 10.47).104 The use of chiral /V-mcthylprolinol as a chiral base catalyst for the Baylis-Hillman reaction of aromatic aldehydes with ethyl acrylate or methyl vinyl ketone gave the adducts in good yields with moderate-to-good enantioselectivities in l,4-dioxane water (1 1, vol/vol) under ambient conditions.105... 

Reactions of 3-aminocrotonic esters with sugar nitro-olefins give 3-(pentaacetoxypen-tyl)pyrroles (Eq. 10.6).8... 

Vinyl epoxides are highly useful synthetic intermediates. The epoxidation of dienes using Mn-salen type catalysts typically occurs at the civ-olefin. Epoxidations of dienes with sugar-derived dioxiranes have previously been reported to react at the trans-olefin of a diene. A new oxazolidinone-sugar dioxirane, 9, has been shown to epoxidize the civ-olefin of a diene <06AG(I)4475>. A variety of substitution on the diene is tolerated in the epoxidation, including aryl, alkyl and even an additional olefin. All of these substitutions provided moderate yields of the mono-epoxide with good enantioselectivity. 

Moisture gradient, 9 97 Moisture levels, in sugar, 23 472 Moisture permeability, 10 2 Moisture permeability, of higher olefin polymers, 20 423-424 Moisture properties, of polyamide fibers, 19 744-745... 

Michael additions to sugar nitro olefins have received considerable less attention than the Henry reaction involving nitro sugars. Early examples of Michael addition include the synthesis54 of licoricidin by Paulsen in 1982, the addition of phosphorous nucleophiles to a D-glucose based nitro olefin55 by Yamashita in 1987 and the synthesis of the natural antibiotic polyoxin published by Barret in 1990.56... 

The synthesis of these important compounds is very well explored. They can be now prepared almost routinely by a number of methods including the RCM cyclization of the properly activated sugar diolefins, 1,3-dipolar cycloaddition of nitrones and olefins (recent review ref. 6) or other types of cyclizations. 

Anomeric hydroperoxides are readily prepared by treatment of 2-deoxy sugars with H202 in the presence of acid (Fig. 59). They are used as reagents for enantioselective epoxidation of a,(Tunsaturated olefins (e.g. chalcone) in the presence of sodium hydroxide, the epoxidations showed exceptionally high asymmetric induction.76... 

Hirst and Woolvin169 preferentially methylated positions 3, 4 and 6 by the use of glucal, an unsaturated sugar derivative having a 1,2-olefinic bond, introduced by the reduction of triacetyl-a-D-glucopyranosyl bromide with zinc dust and acetic acid. By the action of an ethereal solution of perbenzoic acid on an aqueous solution of 3,4,6-trimethyl-glucal a sirupy product was obtained. This was shown to contain... 

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