The protected chalcones 6 8 prepared from acetophenone and henzaldehydes rearranged to the dimethoxypropanone derivatives 9-11 in the presence of trimethyl orthoformate by T1(NO3),.3 H20. These compounds could he cyclized to the isoflavones 12-14 in high yields (Scheme 2). The conversion of these isoflavones to the corresponding isoflavanes (model compounds of the phytoalexin glabridin; see Scheme I ) was the main goal of this work. Hydrogenation of 13 and 14 gave the isoflavanes 15 and 16, respectively, and their deprotection the racemic natural product 4-O-demethylvestitoI(l7). Reduction of 13 and 14 yielded different compounds depending on the reducing agent (Scheme 3 ) . The saturated alcohols 2&23 could he obtained with NaBH, or LiBH4. They were transferred into the raccmic 9-0-demethylmedicarpin (24) and haginin D (25) under acidic conditions. The ketones 2 6 2 8 (Scheme 4) were obtained in high yields by reduction of 12-14 with DIBAH. Deprotection of 26 yielded the racemic 2Jdihydrodaidzein (29). Compounds 13 and 27 as well as 20 and 22 showed different hehaviour under reduction conditions with Li in liquid ammonia. An efficient method for the introduction of the MeOCH,O and the MeOCH2CH20CH2 protecting groups into hydroxylated benzaldehydes and acetophenones (Scheme 5 ) is described. The appropriate experimental conditions depend on the regioselectivity and on the number of the protected groups. The protected aldehydes, especially those with a protected ortho OH group, show an extraordinary ionization hehaviour in chemical-ionization mass spectrometry (isohutane; Scheme 6 ) .Einleitung. -Bei biochemischen Untersuchungen an der Ganzpflanze und an Zellkulturen von Ornithopus sativus BROT. wurde kiirzlich das Phytoalexin Glabridin [ 11 gefunden. Wir haben die Absicht, die Biosynthese dieser Verbindung abzuklaren. Eine Kurzfassung des wahrscheinlichen Biosyntheseweges findet sich im Schema 1. Nachdem bereits die ersten enzymatischen Schritte bis zur Chalconsynthase nachgewiesen wurden [ ll, war es notwendig, fur die Abklarung des weiteren Verlaufes der Biosynthese (2'-Hydroxylase, Reduktase, Prenylase, Cyclase) insbesondere iiber Weg A oder B einige postulierte Vorliiufer herzustellen und diese als Substrate fur geplante Enzymversuche einzusetzen.Die chemische Synthese von hydroxylierten Isoflavanen aus entsprechenden Isoflavonen erfolgte bisher unter Verwendung der Benzyl-Schutzgruppe [2], die hydrogenolytisch abspaltbar ist. Im Falle der Verbindungen vom Typ Phaseollinisoflavan oder Glabridin, die noch eine zusatzliche hydrierbare Doppelbindung aufweisen, versagt die Benzyl-Schutzgruppen-Technik. Es musste demzufolge eine andere geeignete Reaktionssequenz angewendet werden. Ferner sollten diese Synthesen auch zur Isotopenmarkierung vermeintlicher Vorlaufer geeignet sein.

As a part of continuing interest in the zip reaction, we present the results on a carbon ring-enlargement reaction of activated ketones with a CN group as a charge stabilizer. Two series of (l-cyano-2-oxocy-cloalky1)alkanoates were prepared from 8and 12-membered cyano-ketones 1 and 2, respectively, namely the propanoates 3 and 4, the butanoates 6 , s and 9 as well as the pentanoates 12 and 15. While treatment with t-BuOK of the former two homologous esters resulted in both ring enlargement and competitive transesterification, the pentanoates 12 and 15 afforded mostly the diastereoisomeric mixtures of bicyclic alcohols 2Oa-c and 31a,b, respectively, which remained intact on further exposure to base. It was shown thatapart from the base used (C-BuOK us. Li(i-Pr),Nthe distribution of products was greatly influenced by the ring size of substrates. This is further illustrated by treatment of ketones 34 and 35 with t-BuOK. While the former rearranged smoothly to diketone 36, no reaction at all took place with the latter. The behavior of the substrates is discussed in terms of steric and energetic reasons.

Synthesis of 12‐Cyano‐15‐hexadecanolide by Ring Enlargement of 1‐(3′‐Hydroxybutyl)‐2‐oxocyclododecane‐1‐carbonitrile In the presence of Bu4NF, 2‐oxocyclododecane‐1‐carbonitrile (1) reacted with acrylaldehyde to form the corresponding aldehyde 2 which was methylated, e.g. with CH3 Ti[OCH(CH3)2]3. The resulting 1‐(3′‐hydroxybutyl)‐2‐oxocyclododecane‐1‐carbonitrile (5) was converted to 12‐cyano‐15‐hexadecanolide (6) in nearly quantitative yield under the influence of Bu4NF.