TY - THES A1 - Kunz, Oliver T1 - Die Ringschlussmetathese-/elektrozyklische Ringöffnungssequenz : Entwicklung und Anwendung in der Synthese von Z,E-Diencarbonsäuren Y1 - 2013 CY - Potsdam ER - TY - JOUR A1 - Schmidt, Bernd A1 - Kunz, Oliver T1 - Stereoselective synthesis of dienyl phosphonates via extended tethered ring-closing metathesis JF - Organic letters N2 - Allylphosphonates of allylic alcohols were converted to conjugated dienyl phosphonates in a one-flask reaction, comprising a ring-closing metathesis (RCM), a base-induced ring-opening, and an alkylation. The ring-opening proceeds with very high diastereoselectivity, giving exclusively the (1Z,3E)-configured dienes. Single diastereomers and mixtures of diastereomers can be used as starting materials without noticeable effect on the diastereoselectivity of the sequence. Y1 - 2013 U6 - https://doi.org/10.1021/ol4020078 SN - 1523-7060 SN - 1523-7052 VL - 15 IS - 17 SP - 4470 EP - 4473 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Schmidt, Bernd A1 - Kunz, Oliver T1 - Bidirectional cross metathesis and ring-closing metathesis/ring opening of a C-2-symmetric building block: a strategy for the synthesis of decanolide natural products JF - Beilstein journal of organic chemistry N2 - Starting from the conveniently available ex-chiral pool building block (R,R)-hexa-1,5-diene-3,4-diol, the ten-membered ring lactones stagonolide E and curvulide A were synthesized using a bidirectional olefin-metathesis functionalization of the terminal double bonds. Key steps are (i) a site-selective cross metathesis, (ii) a highly diastereoselective extended tethered RCM to furnish a (Z,E)-configured dienyl carboxylic acid and (iii) a Ru-lipase-catalyzed dynamic kinetic resolution to establish the desired configuration at C9. Ring closure was accomplished by macrolactonization. Curvulide A was synthesized from stagonolide E through Sharpless epoxidation. KW - dienes KW - enzyme catalysis KW - lactones KW - metathesis KW - natural products KW - ruthenium Y1 - 2013 U6 - https://doi.org/10.3762/bjoc.9.289 SN - 1860-5397 VL - 9 SP - 2544 EP - 2555 PB - Beilstein-Institut zur Förderung der Chemischen Wissenschaften CY - Frankfurt, Main ER - TY - JOUR A1 - Schmidt, Bernd A1 - Kunz, Oliver T1 - alpha,beta-Unsaturated delta-Valerolactones through RCM-Isomerization Sequence JF - Synlett : accounts and rapid communications in synthetic organic chemistry N2 - alpha,beta-Unsaturated d-lactones are accessible via a sequential ring-closing metathesis (RCM) double-bond migration reaction starting from butenoates of allyl alcohols. This approach proceeds efficiently with lower catalyst loadings and higher initial substrate concentrations compared to the alternative RCM of acrylates derived from homoallylic alcohols. KW - ruthenium KW - lactones KW - tandem reactions KW - metathesis KW - esters Y1 - 2012 U6 - https://doi.org/10.1055/s-0031-1290488 SN - 0936-5214 IS - 6 SP - 851 EP - 854 PB - Thieme CY - Stuttgart ER - TY - JOUR A1 - Schmidt, Bernd A1 - Kunz, Oliver A1 - Petersen, Monib H. T1 - Total syntheses of naturally occurring seimatopolide a and its enantiomer from chiral pool starting materials using a bidirectional strategy JF - The journal of organic chemistry N2 - Enantioselective total syntheses of both enantiomers of the recently isolated decanolide natural product seimatopolide A are described. The C-2-symmetric building blocks (R,R)-hexa-1,5-diene-3,4-diol (derived from D-mannitol) and its enantiomer (derived from L-(+)-tartrate) serve as key starting materials, which are elaborated in a bidirectional way using a selective mono-cross-metathesis, regio- and stereoselective epoxidation, and regioselective reductive epoxide opening to furnish the first fragment. Both enantiomers of the second fragment, 3-hydroxypent-4-enoic acid, were conveniently obtained through a lipase-catalyzed kinetic resolution and merged with the first fragment via Shiina esterification. An E-selective ring-closing metathesis was used to access the 10-membered lactone. A comparison of the specific optical rotations of synthetic seimatopolides with those reported for the natural product suggests that the originally assigned (3R,6R,7R,9S)-configuration should be corrected to (3S,6S,7S,9R). Y1 - 2012 U6 - https://doi.org/10.1021/jo302359h SN - 0022-3263 VL - 77 IS - 23 SP - 10897 EP - 10906 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Schmidt, Bernd A1 - Kunz, Oliver T1 - One-Flask tethered ring closing Metathesis-Electrocyclic ring opening for the highly stereoselective synthesis of conjugated Z/E-Dienes JF - European journal of organic chemistry N2 - A one-flask reaction sequence comprising ring closing metathesis (RCM) of butenoates derived from allylic alcohols and a base-mediated ring opening gives 2Z,4E-configured dienoic acids in high yields and stereoselectivities. Application of the method to the synthesis of the natural product fusanolide A suggests that the originally published structure was erroneously assigned and should be revised. KW - Natural products KW - Lactones KW - Macrocycles KW - Metathesis KW - Carboxylic -acids Y1 - 2012 U6 - https://doi.org/10.1002/ejoc.201101497 SN - 1434-193X IS - 5 SP - 1008 EP - 1018 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schmidt, Bernd A1 - Audoersch, Stephan A1 - Kunz, Oliver T1 - Stereoselective Synthesis of 2Z,4E-Configured Dienoates through Tethered Ring Closing Metathesis JF - Synthesis KW - allyl alcohols KW - dienes KW - ring closing metathesis KW - ruthenium KW - elimination Y1 - 2016 U6 - https://doi.org/10.1055/s-0035-1562536 SN - 0039-7881 SN - 1437-210X VL - 48 SP - 4509 EP - 4518 PB - Thieme CY - Stuttgart ER -