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"Chiral pool" compounds possessing well defined stereocenters and suitable functionality serve as excellent building blocks for the synthesis of natural products and therapeutically important compounds. Tartaric acid is a C2 -symmetric molecule available in both enantiomeric forms. It was extensively utilized in the synthesis of privileged chiral ligands/catalysts such as TADDOLs, and as a start point in the synthesis of plethora of compounds. The advent of several new C-C bond forming reactions offers opportunity for the development of novel synthetic strategies based on chiral pool compounds. We found that the desymmetrization of the bis-dimethyl amide/Weinreb amide derived from tartaric acid can be accomplished by controlled addition of Grignard /organolithium reagents leading to the mono keto amides, the reduction of which affords the γ-hydroxy amides. This account describes our research efforts of more than a decade on the synthesis and application of diverse γ-hydroxy amides derived from tartaric acid in the total synthesis of structurally simple to complex bio-active natural products.

Total synthesis of THP tethered pyrone containing natural product cryptopyranmoscatone B2 was accomplished from commercially available 2-deoxyribose. The key THP unit was assembled by FeCl3 catalyzed cyclization of an allyl alcohol. Brown allylation and RCM reactions were employed to construct the lactone unit. The synthesis represents the first total synthesis of the putative structure of the natural product.

The HOIP ubiquitin E3 ligase generates linear ubiquitin chains by forming a complex with HOIL‐1L and SHARPIN in mammals. Here, we provide the first evidence of linear ubiquitination induced by a HOIP orthologue in Drosophila. We identify Drosophila CG11321, which we named Linear Ubiquitin E3 ligase (LUBEL), and find that it catalyzes linear ubiquitination in vitro. We detect endogenous linear ubiquitin chain‐derived peptides by mass spectrometry in Drosophila Schneider 2 cells and adult flies. Furthermore, using CRISPR/Cas9 technology, we establish linear ubiquitination‐defective flies by mutating residues essential for the catalytic activity of LUBEL. Linear ubiquitination signals accumulate upon heat shock in flies. Interestingly, flies with LUBEL mutations display reduced survival and climbing defects upon heat shock, which is also observed upon specific LUBEL depletion in muscle. Thus, LUBEL is involved in the heat response by controlling linear ubiquitination in flies.

Synthesis of novel C2-symmetric 1,2- 1,3- and 1,4- bis-sulfinamides and their use as effective ligands in rhodium (I) catalyzed asymmetric conjugate addition of arylboronic acids to cyclohexenone and cyclopentenones is described. C2-symmetry as well as chirality at the sulfur center in the ligand is crucial for the high enantioselectivity in the 1,4-addition reaction. It was also observed that the conjugate addition proceeded with good selectivity with Wilkinson's catalyst as the rhodium source.

The synthesis of 2,3,4,6-tetrasubstituted tetrahydropyran unit of ratjadone A was achieved. Pivotal reaction sequence in the synthesis include non-Evans syn aldol reaction of a chiral aldehyde obtained from l -malic acid and Uenishi’s palladium catalyzed stereoselective intramolecular SN2′ reaction to form the tetrahydropyran ring.

A facile ring opening of furans in furyl propargyl alcohols to the corresponding saturated gamma-keto esters is observed in the gold(III) chloride catalyzed reaction with MeOH. It is found that the ring opening of furan is driven by the intramolecular hydroalkoxylation. Mitigating the intramolecular hydroalkoxylation led to the expected conjugated enyne resulting from the dehydration. (C) 2015 Elsevier Ltd. All rights reserved.

A novel ring contraction/rearrangement sequence leading to functionalized 2,8-oxymethano-bridged di- and triquinane compounds is observed in the reaction of various substituted 1-methyl-4-isopropenyl-6-oxabicylo[3.2.1]octan-8-ones with Lewis acids. The reaction is novel and is unprecedented for the synthesis of di- and triquinane frameworks.

Chiral 2-pyridylsulfinamides were shown to be effective catalysts in the alkylation of aryl and alkyl aldehydes with diethylzinc providing the corresponding alcohols in excellent enantioselectivity. Sulfinamide catalysts possessing solitary chirality at the sulfur center produced the product phenethyl alcohol in good enantioselectivity. Diastereomeric sulfinamides possessing chirality at the carbon-bearing nitrogen and at the sulfur of the sulfinamide increased the enantioselectivity of the product alcohols up to >99%. However, there is no effect of the match-mismatch pair of sulfinamide diastereomers on the outcome of the chiral induction of the product phenethyl alcohols. It was conclusively proved that chirality at the sulfur center is mandatory for obtaining good enantioselectivity in the reaction.

Formation of a 2,3-dihydro-4H-pyran containing 14-membered macrocycle by sequential olefin cross metathesis and a highly regiospecific hetero Diels–Alder reaction was observed in the reaction of a hydroxydienone derived from tartaric acid with Grubbs' second generation catalyst. It was found that the free alcohol in the hydroxyenone led to the macrocycle formation, while protection of the hydroxy group formed the ring closing metathesis product.

Synthesis of isochromanones and isoquinolones comprising a quaternary center with high diastereoselectivity was realized via a AuCl3 catalyzed tandem intramolecular exo-dig heterocyclization/enol isomerization/Claisen rearrangement sequence in excellent yields. The reaction is general and amenable for the synthesis of structurally diverse analogues.

A straightforward strategy for the synthesis of (+)-pinellic acid in 16% overall yield and 13 steps, starting from (1R)-1-(furan-2-yl)hexan-1-ol, is described. Key reactions in the synthesis include a Sharpless kinetic resolution, oxidation of a protected furan to reveal a but-2-ene-1,4-dione moiety, and an asymmetric reduction.

A concise and expeditious approach for the total synthesis of bioactive styryllactone (–)-crassalactone C is presented from tartaric acid. The main features of the synthesis include the desymmetrization of dimethylamide of tartaric acid and the effective use of cinnamoyl ester as a protecting group as well as a reactant in the ring-closing metathesis reaction.

A stereoselective total synthesis of (+)-cladospolide A from d -ribose is described. Key features of the synthesis include olefin cross metathesis and Yamaguchi lactonization.

The total synthesis of the enantiomer of the tetrahydrofuran containing natural product Jaspine B is reported. The key reactions in the synthesis include formation of the tetrahydrofuran unit by an acid mediated Williamson etherification and a subsequent elaboration with an olefin cross metathesis reaction.

The enantioselective total synthesis of the diyne containing natural products panaxytriol and (3S,10R)-panaxydiol from l -tartaric acid is reported. Key steps in the synthesis include the elaboration of a γ-hydroxy amide derived from tartaric acid to the required alkyne and the formation of the desired diyne unit by a Cadiot–Chodkiewicz coupling.

The enantioselective synthesis of the natural products cladospolide B, cladospolide C, and iso-cladospolide B has been accomplished from tartaric acid. Key reactions in the synthetic sequence include the elaboration of a gamma-hydroxy amide derived from tartaric acid via alkene cross metathesis, Yamaguchi lactonization, and ring closing metathesis. (C) 2011 Elsevier Ltd. All rights reserved.

The stereoselective synthesis of synargentolide A, a polyhydroxy δ-lactone, has been accomplished from tartaric acid. The key steps in the synthesis involve Keck and Brown allylations and ring closing metathesis.

The formal total synthesis of (+)-didemniserinolipid B, a marine tunicate possessing a 6,8-dioxabicyclo3.2.1]octane framework, was accomplished starting from L-(+)-tartaric acid. The key transformations in the synthesis include the elaboration of a gamma-hydroxy-amide readily obtained by desymmetrization of tartaric acid bis-amide via the controlled addition of a Grignard reagent followed by stereoselective reduction of the resulting ketone. (C) 2010 Elsevier Ltd. All rights reserved.

The enantiodivergent formal syntheses of both enantiomers of aspercyclide C is accomplished. Starting from L-(+)-tartaric acid, the key protected allylic alcohol, (3R,4R)-4-(methoxy-methoxy) non-1-en-3-ol is prepared, and is then elaborated into both enantiomers of 3-(4-methoxybenzyl)oxy]non-1-en-4-ol via Mitsunobu inversion. Esterification with a known biaryl acid, followed by ring-closing metathesis and deprotection completes the syntheses.

A facile approach for the enantiospecific synthesis of the bioactive butanolide (−)-muricatacin from l-(+)-tartaric acid is presented. Pivotal reaction sequence includes the elaboration of γ-hydroxy amide derived from tartaric acid and ring-closing metathesis.

An enantiospecific synthesis of cyclohexane-1,2,3,4-tetrols was accomplished from l-(+)-tartaric acid. Pivotal steps in the synthetic sequence include zinc-mediated Boord-type fragmentation of an acetonide, ring-closing metathesis (RCM), and osmium-mediated dihydroxylation.

The stereoselective total synthesis of (+)-pinellic acid, a natural product used in the treatment of influenza, was accomplished from l -(+)-tartaric acid. A key feature of the synthesis includes the elaboration of a γ-hydroxybutyramide derived from l -(+)-tartaric acid.

A facile ring opening of furans in furyl propargyl alcohols to the corresponding saturated gamma-keto esters is observed in the gold(III) chloride catalyzed reaction with MeOH. It is found that the ring opening of furan is driven by the intramolecular hydroalkoxylation. Mitigating the intramolecular hydroalkoxylation led to the expected conjugated enyne resulting from the dehydration. (C) 2015 Elsevier Ltd. All rights reserved.

Stereoselective synthesis of the bioactive styryllactones (+)-9-deoxygoniopypyrone, (+)-goniopypyrone and (+)-7-epi-goniofufurone has been achieved from d-(-)-tartaric acid. The key step involves the elaboration of a trihydroxy ester to the title compounds utilizing high-yielding stereoselective transformations.

The stereoselective synthesis of (−)-6-acetoxyhexadecanolide was achieved from the readily available chiral pool compound, l-(+)-tartaric acid. The synthetic sequence includes the elaboration of an α-benzyloxy aldehyde derived from tartaric acid with ring closing metathesis as the key step.

The enantioselective synthesis of α-benzyloxy aldehydes containing a terminal alkene was carried out from chiral pool l -(+)-tartaric acid by employing the stereoselective reduction of a 1,4-diketone as the key step. The synthetic utility of these aldehydes was demonstrated in the synthesis of pine beetle pheromones (+)- exo -brevicomin, (+)-iso- exo -brevicomin and a formal synthesis of 2,7- cis -disubstituted oxepane (−)-isolaurepan.

Both antipodes of α-methyl-α-methoxyarylacetic acid derivatives were prepared from a common chiralpool precursor l -(+)-tartaric acid. The key step involves the addition of Grignard reagents to 1,4-diketones derived from tartaric acid. The utility of this strategy was applied in the formal enantioselective synthesis of pine beetle pheromone (−)-frontalin.

A systematic investigation of the reduction and Grignard reagents addition to 1,4-diketones derived from tartaric acid was carried out. It was found that the reduction proceeded with high selectivity using K-Selectride as the reducing agent; while Grignard reagent addition was highly dependent on structure of the dione as well as on the Grignard reagent. The resultant 1,4-diols represent a series of novel TADDOL analogues.

Stereoselective synthesis of boronolide and 5-epi-boronolide was achieved from d -(−)-tartaric acid. The key step involves the reduction of a keto Weinreb amide for the synthesis of boronolide, and a single pot construction of a diketone from the bis-Weinreb amide of tartaric acid and subsequent reduction with L-Selectride for 5-epi-boronolide.

An enantiospecific synthesis of (−)-2-hydroxy- exo -brevicomin was achieved from l -(+)-tartaric acid in high yield. The key step involves a very highly diastereoselective reduction of a keto Weinreb amide.

Stereoselective synthesis of a series of 2-aryl-2-methoxyethanols was achieved from inexpensive chiral pool tartaric acid employing a diastereoselective reduction of a symmetrical 1,4-diaryldiketone as the key step. 2-Aryl-2-methoxyethanols were enantioselectively prepared in 80-90% yield.

Diastereomerically pure (+)- and (−)-2,2-dimethyl-1,3-diphenyl-1,3-propanediols were synthesized starting from diethyl malonate and resolved through diesters of (−)-camphanic acid and also N-carbethoxy- l -proline. The absolute configuration of the (−)-enantiomer was established by X-ray crystallography.

Enantiospecific synthesis of (-)-muricatacin, a bio-active lactone comprising of a 5-hydroxyalkylbutan-4-olide structural component has been achieved from L-(+)-tartaric acid. The key step involves a disteroselective reduction of a $C_2$-symmetric 1,4-diketone derived from tartaric acid followed by a selective Grignard reagent addition.

The enantioselective alkylation of aldehydes with diethylzinc is achieved in the presence of a chiral sulfinamide as optimal catalyst.

2-Thienyl and 2-furyl carbinols are prepared in good enantiomeric excess (up to 93% ee ) through oxazaborolidine catalysed reduction of the corresponding ketones.

Enantioselective synthesis of \alpha-hydroxy aldehydes with an alkene tether was accomplished front L-(+)-tartaric acid, employing stereoselective reduction of a 1,4-diketone with L-selectride as the key step. Synthetic utility of these aldehydes was demonstrated in the synthesis of pine beetle pheromone (+)-exo-brevicomin.

Synthesis of isochromanones and isoquinolones comprising a quaternary center with high diastereoselectivity was realized via a AuCl3 catalyzed tandem intramolecular exo-dig heterocyclization/enol isomerization/Claisen rearrangement sequence in excellent yields. The reaction is general and amenable for the synthesis of structurally diverse analogues.

A systematic study was conducted to formulate the optimal reaction parameters for the oxazaborolidine catalysed enantioselective reduction. The catalyst derived from diphenyl prolinol was found to be the best amongst several other analogues and a reduction temperature of 45 °C is recommended for high enantioselectivity (92–99% ee ) for the reduction of alkyl aryl ketones.

Various dialkoxides of zinc, magnesium and boron were examined for the enantioselective addition of diethylzinc to aryl aldehydes. Only zinc based reagent catalysed the reaction effectively providing up to 89% ee of the product.

A formal total synthesis of the 20-membered marine macrolide, palmerolide A from chiral pool tartaric acid is described. Elaboration of a γ-hydroxy amide, which is derived from the desymmetrization of tartaric acid amide, and Boord olefination are the pivotal reactions employed for the synthesis of the chiral building blocks, and Stille coupling and ring-closing metathesis (RCM) are used to assemble the macrolactone.

Various dialkoxides of zinc, magnesium and boron were examined for the enantioselective addition of diethylzinc to aryl aldehydes. Only zinc based reagent catalysed the reaction effectively providing up to 89% ee of the product.

An aza-Darzens reaction, involving the addition of chloromethylphosphonate anions to enantiopure sulfinimines, has been developed for the asymmetric synthesis of aziridine 2-phosphonates. Best results involve cyclization of the syn and anti diastereomerically pure alpha-chloro-beta-amino phosphonates to cis- and trans-N-sulfinyl aziridine 2-phosphonates, respectively, with n-BuLi. A transition-state hypothesis is proposed wherein the chloromethylphosphonate anion adds to the C-N bond on the side that is opposite the bulky p-tolyl sulfinyl group. The N-sulfinyl group is easily removed by treatment with MeMgBr or TFA/MeOH, which affords the NH-aziridines in good yield. Using transfer hydrogenation conditions, the NH-aziridines were regioselectively opened to the corresponding enantiopure alpha-amino phosphonates without N-activation and in excellent yield.

Enantiospecific synthesis of bio-active butenolide (+)-iso-cladospolide B from D-(-)-tartaric acid in a short synthetic sequence is presented. Pivotal reaction sequence includes cross metathesis of an alkene and Wittig olefination. (C) 2010 Elsevier Ltd. All rights reserved.