Conduritol synthesis

In laboratory synthesis, these catalysts have been utilized primarily to form both common and large rings by coupling two terminal alkenes.295 For example, catalyst H has been used to synthesize the highly oxygenated cyclohexenes known as conduritols. 

The stoichiometric approach has been successfully used as the key step for the synthesis of biologically active compounds, to obtain enantioenriched allylic alcohols, as illustrated by the synthesis of conduritols derivatives 84 or the aggregation pheromone of the Douglas-fir beetle 85 , as well as enantioenriched oxiranes, intermediates for the synthesis of (—)-isomenthone 86 ° (Scheme 34). 

M. C. McIntosh and S. M. Weinreb, A strategy for synthesis of conduritols and related cyclitols via stereodivergent vinylsilane-aldehyde cyclizations, J. Org. Chem. 56 5010 (1991). 

The kinetic resolution of C2-symmetric racemic substrate as shown in Scheme 8E.22 requires differentiation between the starting material and the monoalkylated product 113 in addition to the enantiodiscrimination in the ionization step. With a bulky carboxylic acid as nucleophile, the racemic tetraacetate of conduritol B was efficiently resolved under phase-transfer conditions [68]. Further elaboration of the hydrolytically desymmetrized alcohol resulted in the synthesis of the important glycosidase inhibitor, (+)-cyclophellitol. 

Scheme 8E.22. Kinetic resolution of conduritol B and synthesis of cyclophellitol.

Finn KJ, Collins J, Hudlicky T (2006) Toluene Dioxygenase-Mediated Oxidation of Dibromobenzenes. Absolute Stereochemistry of New Metabolites and Synthesis of (-)-Conduritol E. Tetrahedron 62 7471... 

The elegant asymmetrization methodology of a meso compound, achieved in high enantioexcess under chiral environment, was the highlight of the total synthesis of (+)-pancratistatin (94) reported by Trost and Pulley (31]. The synthesis commenced with ( )-conduritol-A (130), obtained from p-benzoquinone, (Scheme 18) which was converted into the acetonide 131 and thence, via the dialkoxide to the cis-bis carbonate 132 (Scheme 19). The chiral n-ailyl palladium complex A formed on treatment erf 132 with the catalyst generated from chiral bis-amide 133 and n-allyl palladium chloride underwent azide substitution from the less hindered face of the molecule to provide the monocarbonate 134 in excellent yield and with high optical induction. 

Ley SV, Redgrave AJ (1990) Microbial oxidation in synthesis concise preparation of (+)-conduritol F from benzene. Synlett 1990 393-394... 

Dumortier, L. et al. Chemo-Enzymatic Total Synthesis of Some Conduritols, Carbasugars and (+)-Fortamine. 1998 [90]... 

Polyhydroxylated cyclohexene derivatives such as conduritol A-F (7-12) are important secondary messengers eliciting a wide range of biological responses and have also been widely used as starting materials for advanced organic synthesis (4). RCM opens a particularly concise entry into this class of compounds, not least because of the ready availability of the required cyclization precursors from abundant monosaccharides (5,6). 

C104 (L-glycoside), 95f 101-102 Chaetiacandin, 101-102,104 Concanavalin-A, 146-148 Conduritols, 2-4 Cycloalkene synthesis. See Ascidiatrienolide A Herbarumins Pinolidoxin... 

Mehta G, Lakshminath S (2000) A norbornyl route to cyclohexitols stereoselective synthesis of conduritol-E, alio-inositol, MK 7607 and gabosines. Tetrahedron Lett 41 3509... 

Cyclitols. A novel synthesis of conduritol (6) from benzoquinone utilizes 1 for protection of one C=C bond and for differentiation of the carbonyl groups. Reaction of the quinone with 1 gives the Diels-Alder adduct 2, which is converted selectively into 4,... 

Finally for this section, as another asymmetric synthesis of cycliphelitol (1), the synthetic effort of Trost s group will be introduced [52]. Their synthesis was conducted based on the palladium-catalyzed kinetic resolution of racemic conduritol B tetraacetate ( )-94. Since racemic... 

Metha, G. et al. A Norbornyl Route to Cyclohexitols Stereoselective Synthesis of Conduritol-E, aWo-Inositol, MK 7607 and Gabosines. 3.3 2000 [154]... 

Kna 7 has used the oxyanion-accelerated rDA reaction to advantage in the synthesis of conduritol A. The masked dienol used was 9-[(benzyloxy)methoxy]anthracene (81), which upon reaction with benzo-quinone (82) gave the protected adduct (83) (equation 38). Further transformations yielded (84), which upon treatment with potassium hydride caused rDA fragmentation to occur at 35 °C. Two subsequent steps produced conduritol A (86a), a naturally occurring cyclitol, in 39% overall yield from (82). The room-temperature DA activity of anthranol reported by Rickbom, coupled with the observed low-temperature rDA reactivity of its adducts, makes anthranol a highly useful alkene protecting group via a DA/iDA sequence. 

D-Xylose derivative 7 has a latent plane of symmetry, the terminal hydroxyl and carbonyl groups being virtually enantiotopic. With adapted reactions and a judicious order of performing them (Scheme 4), the two enantiomeric intermediates 8 and ent-S were prepared [45], They are interesting starting materials for further diastereodivergent synthesis of conduritol and inositol derivatives [46],... 

D-Xylose has been used as starting material in the synthesis of (+)-Conduritol C [88] and cyclophellitol [56] (Scheme 12). The combinatitMi of the zinc-mediated tandem reaction with RCM was also used in the synthesis of 7-deoxypancratistatin, a naturally occurring compound with activities against different cancer types. In the latter synthesis, the longest reaction sequence involves 13 steps from o-xylose with a 4% overall yield [58] (Scheme 12). 

The new olefin synthesis was also used for a simple synthesis of tetra-O-acetyl-conduritol-B, tetra-0-acetyl-( )-cyclohexene-l, 3/2,4-tetrol (9),from 1,4,5,6-tetra-O-acetyl myoinositol (7).2... 

Weak bases can also induce ring opening with the aid of an oxaphilic reagent. Thus, the oxygen bridge in oxabicyclo[2.2.1]heptanone 177 was cleaved in the presence of triethylamine and TMSOTf to generate enone 178, which was an intermediate in the first total synthesis of (-)-conduritol C, Eq. 114 [93]. TBDMSOTf/triethylamine is also an effective combination for this transformation and has been used in the synthesis of myo-inositol derivatives, as well as (-)-conduritol B from 179, Eq. 115 [167,168]. (+)-Conduritol F has also been prepared by this route which served to confirm its structure and demonstrate it was identical to natural (+)-leucanthemitol [168], Fig. 5. 

Y.-U. Kwon, C. Lee, and S.-K. Chung, Facile synthesis of all possible diasteromers of conduritol and various derivatives of inositol, stereoisomers in high enantiopurity from myo-inositol, J. Org. Chem., 67 (2002) 3327-3338. 

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