An enantioselective synthesis of cryptocarya diacetate

[reaction: see text]. The enantioselective synthesis of cryptocarya diacetate has been achieved in 10 steps from ethyl sorbate. The route relies upon an enantio- and regioselective Sharpless dihydroxylation and a palladium-catalyzed reduction to form a delta-hydroxy-1-enoate, which was subsequently converted into a benzylidene-protected 3,5-dihydroxy carboxylic ester. This ester was converted into cryptocarya diacetate in 14% overall yield via an allylation and methathesis ring closure reaction sequence.     

First stereoselective total synthesis of Neocosmosin A: a facile approach

First stereoselective concise synthesis of Neocosmosin A, with in vitro binding affinity for human opioid and cannabinoid receptors, has been reported using readily available starting materials such as methylacetoacetate, cyclohexanone, and homoallyl alcohol involved in the key transformations. There are three fragments involved in the synthesis of target molecule, bearing acid functionality, (R)-pent-4-en-2-ol, and Weinreb amide which are synthesized in four, eight, and three steps, respectively. Then the fragments were coupled in four steps to yield the target molecule in an overall yield of 28.6%.     

A short stereoselective total synthesis of the fusarium toxin equisetin

A short stereoselective synthesis of the fusarium toxin equisetin, an N-methylserine-derived acyl tetramic acid and potent inhibitor of HIV-1 integrase enzyme, is described using as the key step a stereoselective lithium perchlorate mediated intramolecular Diels-Alder reaction of a fully conjugated E,E,E-triene with a trisubstituted gamma,delta-unsaturated beta-ketothioester.     

A simple and efficient approach to 1,3-polyols: application to the synthesis of cryptocarya diacetate

A highly enantio- and stereoselective synthetic strategy for both syn- and anti-1,3-polyols has been developed. The sequence involves iterative Jacobsen's hydrolytic kinetic resolution (HKR), diastereoselective iodine-induced electrophilic cyclization, and ring-closing metathesis (RCM). This protocol has subsequently been utilized for the synthesis of cryptocarya diacetate, a natural product with broad range of biological activity.     

A facile and highly stereoselective synthesis of 1-thiotrehalose

A facile and highly stereoselective synthesis of 1-thiotrehalose, that is, α,α-S-linked trehalose, is described. Glycosylation of configurationally pure α-glucosyl thiol 5 with glucosyl trichloroacetimidate 6 or glucosyl thioimidate 9 followed by deprotection afforded 1-thiotrehalose in excellent α-stereoselectivity and high yield. A different synthetic route to the key building block, α-glucosyl thiol 5, was also investigated in this report.     

A short stereoselective synthesis of (+)-boronolide

A short and stereoselective synthesis of (+)-boronolide via oxidative functionalization of an olefin using a pendant sulfinyl group is described. Diastereoselective allylation was performed using Keck’s protocol and the lactone moiety was prepared by ring closing metathesis.     

A short and stereoselective synthesis of carbocyclic alpha-l-dideoxyhomonucleosides

A stereoselective five-step total synthesis of the hitherto unknown carbocyclic alpha-L-dideoxyhomonu-cleosides starting from readily available (1R,5S)-2-oxabicyclo[3.3.0]oct-6-en-3-one is described.     

A facile total synthesis of rutaecarpine

The indoloquinazoline alkaloid rutaecarpine has been synthesized efficiently by employing 9,10,11,12-tetrahydro-4H-pyrido[2,1-b]quinazoline-4,9-dione (4) as a key intermediate, which was prepared by adapting a Dieckmann condensation-decarboxylation sequence from quinazolinone diester 6.     

A facile one-pot synthesis of 2,5-disubstituted oxazoles using iodobenzene diacetate

A facile one-pot synthesis of oxazoles 1a-h is described that utilizes readily available aromatic α-methyl ketones and a safe hypervalent iodine reagent, iodobenzene diacetate.     

A facile approach to the synthesis of securinega alkaloids: stereoselective total synthesis of (−)-allonorsecurinine

A concise stereoselective total synthesis of alkaloid (−)-allonorsecurinine is described utilizing classical reactions such as Grignard, Aldol and Horner-Wittig reactions as the key steps.     

First stereoselective total synthesis of trichodermone A

The first stereoselective total synthesis of trichodermone A using Baylis-Hillman and ring-closing metathesis (RCM) reactions as key steps is reported.     

A facile synthesis of 1,2-oxaphospholenes and stereoselective conversion into oxaphospholanes

Treatment of α-acylallylphosphonates with m-CPBA in the presence of MgSO₄, afforded 1,2-oxaphosphol-3-enes 2-oxides and the subsequent cuprate addition produced 1,2-oxaphospholanes stereoselectively.     

A short and efficient stereoselective synthesis of dihydrosphingosine triacetate

A highly enantiocontrolled synthesis of -(+)-erythro-dihydrosphingosine (sphinganine) triacetate is described using the Sharpless asymmetric dihydroxylation and the regiospecific nucleophilic opening of a cyclic sulfite as key steps.     

First stereoselective total synthesis of Goniothalesdiol A

The first total synthesis of Goniothalesdiol A, isolated from the stems of Goniothalamus amuyon (Annonaceae) is reported. The C2 stereocentre and C3/C4 syn diol were created by a Sharpless kinetic resolution followed by acetonide formation. The tetrahydropyran ring was formed and the C6 stereocentre was fixed by intramolecular oxy-Michael addition.     

Enantioselective syntheses of cryptocarya triacetate,cryptocaryolone, and cryptocaryolone diacetate

[reaction: see text] The enantioselective syntheses of three natural products from Cryptocarya latifolia have been achieved in 13-15 steps from ethyl sorbate. The route relies upon an enantio- and regioselective Sharpless dihydroxylation and a palladium-catalyzed reduction to establish the absolute stereochemistry. The route also relies upon a highly (E)-selective olefin cross-metathesis reaction to form trans-delta-hydroxy-1-enoates. The resulting delta-hydroxy-1-enoates were subsequently converted into cryptocarya triacetate, cryptocaryolone, and cryptocaryolone diacetate.     

A short and stereoselective synthesis of functionalized pentenomycin derivatives

A short and stereoselective synthesis of 2-hydroxymethyl-4-deoxypentenomycin and 2-hydoxymethylpentenomycin derivatives is accomplished in five and seven steps starting from tetrabromonorbornyl derivatives in overall yields of 41% and 38%, respectively.     

First stereoselective total synthesis of seimatopolide A

The first stereoselective total synthesis of seimatopolide A (1) has been achieved. The key steps are Keck allylation, Sharpless asymmetric dihydroxylation, cross-, and ring-closing metathesis reactions.     

First stereoselective total synthesis of pectinolide A

The enantioselective synthesis of bio-active 5,6-dihydro-α-pyrone, pectinolide A, has been achieved in 10 steps in good overall yield. Of the three stereogenic centres, the C-5/C-6 vic-diol was obtained using diastereo- and enantioselective Brown hydroxyl crotylation, while the C-3′ stereocentre was created by Jacobsen hydrolytic kinetic resolution method.