The possibility of fluoride-mediated selective dephosphonylation of α-diazo-β-carbonyl phosphonates such as the Ohira-Bestmann reagent has been proposed and executed. The resulting α-diazocarbonyl intermediates undergo a (3 + 2)-cycloaddition at room temperature with conjugated olefins and benzynes. Interestingly, under the current conditions, the resulting cycloaddition products underwent either N-acylation (with excess α-diazo-β-carbonyl phosphonates) or Michael addition (with conjugated olefins).

The total synthesis of (+)-petromyroxol ( 1 ) and its seven diastereomers including the (−)- iso -petromyroxol ( 2 ) is described. The employed strategy involves the use of easily available C5-epimeric epoxides 5 and 5′ and nonselective anomeric C1-allylation, proceeding with or without inversion at C2, thereby giving the possibility of synthesizing all possible diastereomers. Extensive two-dimensional (2D) NMR analyses of all eight diastereomers have been carried out to assign the chemical shifts of the central carbons and the corresponding attached hydrogens and to learn how the C/H-chemical shifts of the tetrahydrofuran ring were influenced by the adjacent centers.

The total synthesis of two isomeric hexaketides isolated along with sordarial, whichh ave the proposed relative arabino and ribo configurations, has been executed. A Rh-catalyzed [2+ +2+ +2]-alkyne cyclotrimerization has been employed as the key reactiont oc onstruct the central dihydroisobenzofuran core. The absolute configurationo ft he xy-larinol Bh exaketide has been established as l-arabino.T his is the first natural product of this family for which the absolute configuration has been determined, and this can be extended to provide structural details of several of relatedh exaketides.[a] V. Mullapudi, C. V. Ramana Scheme1.Key retrosyntheticd isconnections for 1 and 2.TBS = tert-butyldimethylsilyl.Scheme2.To tal synthesis of (+ +)-xylarinol B( 1).

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