Insertion, of carbonyl

One of the possible synthetic ways to obtain heterocyclic phosphines is the insertion of carbonyl compounds into the P—E (E = Si, Ge) bond of sila- and germa-phospholanes. Thus, the enlargement of the ring takes place and the P—C—O—E fragment is formed (9) [Eq. (7)] (74MI1 75JOMC35 77JOM35). The heterocyclic phosphepanes are obtained as a mixture of stereoisomers. 

In contrast, Ni(0)-catalysed intramolecular reaction of the diene aldehyde 73 and ketones with hydrosilane proceeds smoothly to give five-, six- and seven-membered alcohols. The 7i-allylnickel species 75 is formed by the reaction of 73 with Ni hydride 74, generated by the oxidative addition of hydrosilane. It is well-known that n-allylnickel reacts with carbonyl as an electrophile (or insertion of carbonyl) to afford... 

To develop new methods for organic synthesis, Woerpel and coworkers exploited the inherent reactivity of di -fc/ f-butylsilacyclopropanes to create new carbon-carbon bonds in a stereoselective fashion (Scheme 7.7).62 They discovered that transition metal salts catalyze the insertion of carbonyl compounds into the strained carbon-silicon bond to form oxasilacyclopentanes. The regioselectivity of insertion could be controlled by the identity of the catalyst. Copper promoted the insertion of croto-naldehyde into the more substituted C-Si bond of 52 to afford oxasilacyclopentane 53,63 whereas zinc catalyzed the insertion of butyraldehyde into the less substituted bond of 52 to provide the complementary product, 54.64 Oxasilacyclopentanes (e.g., 55) could be transformed into useful synthetic intermediates through oxidation of the C-Si bond,65 66 which provided diol 56 with three contiguous stereocenters. 

The efficiency of transmetalation from boron to palladium in the catalytic 1,4-addition of aryl or 1-alkenylboronic acids to enones encouraged us to extend the protocol to the addition of aryl- and 1-alkenylboronic adds to aldehydes in an aqueous solution (Eq. 4). The insertion of carbonyl groups into transition metal-carbon bonds has not received much attention, but the catalytic use of transition metals may allow such addition of various organometallics which are inert without a catalyst, the asymmetric addition using a chiral phosphine complex, or the reaction in an aqueous phase. 

Examples of the insertion of carbonyl compounds into metal-oxygen bonds are shown in Table... 

Although the insertion of carbonyl compounds into the A1—O bond may be important in the Tischenko reaction and in the polymerization of aldehydes by aluminium alkoxides , only the group 14 adducts are well characterized. The adducts usually dissociate readily unless the carbonyl group carries a strongly electron-withdrawing substituent. 

The chemistry of germylphosphines continues to develop. A full report of the insertion of carbonyl compounds and other unsaturated systems, e.g. acrylonitrile, into the Ge—P bond of germaphospholans (103) has now appeared. The Ge—P bond in (103) is cleaved by methoxide ion in methanol to form the secondary phosphine (104), which re-forms the germaphospholan during distillation under reduced... 

The following steps are involved in the proposed mechanism (i) oxidative addition of hydrosilane to the rhodium(I) complex (25) to give 26 (ii) insertion of carbonyl into the resulting silicon-rhodium bond of 26 to form a diastereomeric a-siloxyalkylrhodium hydride intermediate (28) (iii) formation of an optically active silyl ether of the sec-alcohol by reductive elimination, as shown in equation 75. 

Insertion of carbonyl group around a crowded metal center is achieved... 

The indenone 70 is obtained by the reaction of o-iodobenzaldehyde (66) with alkyne [22,23], Two mechanisms are suggested. One of them involves the formation of Pd(IV) species 68 from 67 by oxidative addition of aldehyde, and its reductive elimination affords the indenone 70. Another possibility is the insertion of carbonyl group (or nucleophilic attack) to form the indenyloxypalladium 69, and /i-H elimination gives the indenone 70. 

Insertion of carbonyl (CO) to form esters or amides upon extrusion of metal. ... 

Phosphoric acid Insertion of carbonyl into carbon-carbon bonds via C-didbloromethylation... 

Via intermediates Insertion of carbonyl via C-dichloromethylation Ring expansion of adamantanes... 

The insertion of carbonyl sulfide into a dithiocarbamate ligand has been noted in one instance. Thus, the molybdenum(II) dicarbonyl [Mo(CO)2(S2CNEt2)2]... 

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