A Simpler Route for Making Nitrogen-Alkene Rings

A common nitrogen building block used in many natural product and drug syntheses can now be made in its unprotected form in a single step.</jats:p

ATTEMPTED SYNTHESIS OF BIS-SPIROEPOXIDE DITHIANEDIOXIDE

The bis-spiroepoxide dithiane dioxide has been attempted to be synthesised as its role as an intermediate in the synthesis of diaminopimelic acid (DAP). The first method was carried out by reacting the 3-dithiane-2- diethylphosphonate 4 with an aqueous solution of the commercially available glutaraldehide resulting the bis-ketene dithiane dioxide 5. The second alternative method was involving the ozonolysis of cyclopentene 7 in the synthesis of bis-ketene dithiarie dioxide 5 in four step reactions which gave moderate to good yield. Unfortunately, epoxidation process for the bis-ketene dithiane dioxide 5 was still unsuccess yet

ATTEMPTED SYNTHESIS OF BIS-SPIROEPOXIDE DITHIANEDIOXIDE

The  bis-spiroepoxide  dithiane  dioxide  has  been attempted  to  be  synthesised  as  its  role  as  an  intermediate  in the  synthesis  of  diaminopimelic  acid  (DAP).  The  first  method was  carried  out  by  reacting  the  3-dithiane-2-diethylphosphonate  4  with  an  aqueous  solution  of  the commercially  available  glutaraldehide  resulting  the  bis-ketene dithiane  dioxide  5.  The  second  alternative  method  was involving  the  ozonolysis  of  cyclopentene   7  in  the  synthesis  of bis-ketene dithiane dioxide  5 in  four step reactions  which gave moderate to good yield. Unfortunately, epoxidation process  for the bis-ketene dithiane dioxide 5 was still unsuccess yet.Key  words:  synthesis,  diaminopimelic  acid,  bis-spiroepoxide  dithiane dioxid

Concise Synthesis of (+)-allo-Kainic Acid via MgI2-Mediated Tandem Aziridine Ring Opening-Formal [3+2] Cycloaddition

3-Methyl vinyl aziridine undergoes a mild MgI2-promoted S(N)2' ring opening and concomitant cyclization with fumarate Michael acceptors to give trisubstituted pyrrolidines. The process is efficient and highly diastereoselective. This methodology has been applied to a concise asymmetric synthesis of (+)-allo-kainic acid.</p

Short Convergent Synthesis of the Mycolactone Core Through Lithiation-Borylation Homologations

Abstract: Using iterative lithiation-borylation homologations, the mycolactone toxin core has been synthesized in 13 steps and 17 %o verall yield. The rapid build-up of molecular complexity,h igh convergencea nd high stereoselectivitya re noteworthy features of this synthesis. The third most common Mycobacterium infection( after M. tuberculosis and M. leprae)i sthat of M. ulcerans,t he pathogen responsible for the severeu lcerative skin disease,B uruli ulcer. [1] Endemic in tropical Africa, it infects over 5000 patients per annum with 48 %o fc ases being aged under 15. [1a, 2] Transmission is thought to occur by an aquatic organism bite, [3] with initial manifestation occurring as ap ainless skin nodule. If diagnosed early, simple antibiotic chemotherapyi seffective (80 %), [4] however, if untreated, propagation of the infection results in large skin lesions of necrotic tissue and bone loss which are only treatable througha ggressive surgery,r esulting in scarring and loss of limb function. [1a, c] Small and coworkers [8] successfully isolated milligram quantities of 1 allowing structure elucidation by NMR [17] These efforts have enabled furtherr esearch into the pathogenesis of Buruli ulcer, [18] aid the invention of new/simplerd iagnostic techniques [20a] The side chain of 1 has alreadyb een synthesized by the groups of Kishi, Our retrosynthetic analysisb egan with disconnection to the knowni ntermediate 3 (Scheme 2). We began with the synthesis of boronic ester 10,w hich was achieved in three high yielding steps (Scheme3). Copper-catalyzed formal hydroboration [27] of alkynol 11 with B 2 pin 2 in the presence of MeOH gave the desiredv inyl boronate in 83 % yield as as ingle regio-and stereoisomer.S ubsequent carbaScheme1.Structure of mycolactone A/B 1 and core 2. [a] C. A. Brown, Prof. Dr.V .K.A ggarwal SchoolofC hemistry,University of Bristol Cantock&apos;s Close Bristol, BS8 1TS (UK