Chiral Cyclopentene Research Articles

ChemInform Abstract: Total Synthesis of (-)-Carbovir.

Optically pure (–)-carbovir has been prepared by two different routes involving stereospecific opening of chiral cyclopentene epoxides by substituted purines. Introduction of the 2′,3′ unsaturation was accomplished by mesylate elimination, either after introduction of the purine (Route 1), or earlier in the sequence, producing a novel vinyl epoxide (Route 2).

Asymmetric [3+2] Cycloadditions of Allenoates and Dual Activated Olefins Catalyzed by Simple Bifunctional N‐Acyl Aminophosphines

Bifunctional catalyst: Simple bifunctional N-Acyl aminophosphines such as 1 were developed to catalyze the first asymmetric [3+2] cycloaddition between allenoates and dual activated olefins. The cycloaddition reactions afford multifunctional chiral cyclopentenes with exclusive regioselectivity, and good to excellent enantioselectivity and yields.

Synthesis of enantiomeric cyclosarcomycins

Based on chiral cyclopentene blocks 2 and 3 , enantiomeric cyclosarcomycins 4 and 5 were obtained and characterised.

Synthesis of conformationally locked carbocyclic nucleoside phosphonates to probe the active site of HIV-1 RT

The conformationally locked carbocyclic nucleoside phosphonates 2 and 2' and key intermediates for the synthesis of 3 and 3' were prepared from a chiral cyclopentene derivative and epicholorohydrine, respectively. The structure of the nucleoside precursor 6 was confirmed by X-ray crystallography. These carbocyclic nucleoside phosphonates were designed to probe their binding interactions at the active site of HIV-1-RT.

ChemInform Abstract: Organocatalytic Enantioselective Cascade Michael—Aldol Condensation Reactions: Efficient Assembly of Densely Functionalized Chiral Cyclopentenes.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Enantioselective Cascade Michael-Aldol Condensation Reaction

The authors report an organocatalytic asymmetric Michael-aldol condensation reaction for the generation of chiral cyclopentenes. Diphenyl prolinol trimethyl silyl ether 1 in combination with sodium acetate was found to be the best catalyst system for this reaction. Without the additive the reaction yield was somewhat lower. With 10 mol% of catalyst 1, good yields (63-89%) and excellent enantioselectivities (er = 96:4 to 98:2) are obtained for different α,β-unsaturated aldehydes.

Organocatalytic Enantioselective Cascade Michael–Aldol Condensation Reactions: Efficient Assembly of Densely Functionalized Chiral Cyclopentenes

Organocatalytic Enantioselective Cascade Michael–Aldol Condensation Reactions: Efficient Assembly of Densely Functionalized Chiral Cyclopentenes

Organocatalytic Enantioselective Cascade Michael–Aldol Condensation Reactions: Efficient Assembly of Densely Functionalized Chiral Cyclopentenes

Organocatalytic Enantioselective Cascade Michael–Aldol Condensation Reactions: Efficient Assembly of Densely Functionalized Chiral Cyclopentenes

Asymmetric Silylboronation of Allenes

A variety of allenes were enantio­selectively converted into chiral allyl silyl vinylboro­nate esters in the presence of a silylboronate and a Pd(0)/monodentate phosphine ligand. Yields and enantioselectivities were generally excellent. The reaction can be performed chemoselectively in the presence of an alkyne, and the versatility of the products was demonstrated by conversion into several interesting chiral cyclopentene compounds.

Highly Deoxygenated Sugars. Part 2. Synthesis of Chiral Cyclopentenes via Novel Carbocyclization of C‐4 Branched Deoxysugars.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Highly Deoxygenated Sugars. II. Synthesis of Chiral Cyclopentenes via Novel Carbocyclization of C‐4 Branched Deoxysugars †

Tri‐O‐acetyl‐d‐glucal (1) was converted via Ferrier type II rearrangement with high α‐selectivity to 2,3‐unsaturated methyl glycosides 2a and 2b using ferric chloride as the catalyst. Palladium induced allylic substitution with sodium tert‐butylacetoacetate as a nucleophile leads to C‐4 branched sugars. Subsequent hydrogenation followed by treatment with trifluoroacetic acid affords the highly functionalized chiral cyclopentene derivative 5a as a versatile chiral building block for cyclopentanoids. †Dedicated to Professor Dr. Hans Paulsen on the occasion of his 80th birthday.

Participation of the chiral sulfinyl functionality in palladium-catalyzed asymmetric vinylcyclopropane-cyclopentene rearrangements

Stereochemical studies on the palladium-catalyzed asymmetric 1, 3-rearrangements of [4-chiral arylsulfinyl-1, 3( E or Z)-butadienyl]cyclopropanes to chiral cyclopentenes are described. The plausible mechanism for the rationalization of the stereochemical outcomes is proposed. [Display omitted]

Total synthesis of (–)-carbovir

Optically pure (–)-carbovir has been prepared by two different routes involving stereospecific opening of chiral cyclopentene epoxides by substituted purines. Introduction of the 2′,3′ unsaturation was accomplished by mesylate elimination, either after introduction of the purine (Route 1), or earlier in the sequence, producing a novel vinyl epoxide (Route 2).

Vitamin B 129 a catalyst in the synthesis of prostaglandins

A prostaglandin F 2α precursor containing all structural features from C 6 to C 20 with 8 R, 9 S, 11 R and 12 R chirality is obtained by the one step formation of two C-C bonds in the B 12-catalyzed radical cyclization-addition sequence starting from a chiral cyclopentene bromoacetal and l-octyne-3-one. The B 12-catalyzed radical cyclization-elimination sequence of a chiral cyclopentene precursor leads to (-)-(3a R,6a S)-3,3a,6,6a-tetrahydro-2H-cyclopenta abfuran-2-one. Its (+)-(3a S,6a R-enantiomer is obtained via B 12-catalyzed, enantio- selective isomerization of cyclopentene oxide to (R)-2-cyclopentene-l-ol followed by the B 12-catalyzed radical cyclization-elimination sequence of its bromoacetal.

Optical Activities of Two Steroids Containing a Chiral Cyclopentene Ring

The direction of the optical rotation of the steroid 3 can be reconciled with Brewster's rules, if account is taken of "bond fixation", but the direction of the optical rotation of 2 cannot be.