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A novel oxidative decarboxylation of β,γ-unsaturated carboxylic acids mediated by hypervalent iodine(III) reagents is described. The decarboxylative C–O bond forming reaction proceeded in the presence of PhI(OAc)2 to give the corresponding allylic acetates. In addition, decarboxylative C–N bond formation was achieved by utilizing hypervalent iodine(III) reagents containing an I–N bond. Mechanistic studies suggest the unique reactivity of hypervalent iodine reagents in this ionic oxidative decarboxylation.

A new methodology for the selective reduction and alkylation of carbonyl nitrile groups in substrates also bearing more reactive aldehyde or ketone moieties is developed.

Recent progress in selective transformation of carbonyl groups using in situ protection methodology is described. These techniques which enable reversing reactivity of functional groups have potential usefulness because they can remove complicated protection-deprotection sequences. In this review, we discuss various in situ protection strategies and their synthetic applications.

A novel procedure for the highly selective deprotection of methylene acetals and Mom-groups in the presence of ketal-type protective groups is developed utilizing a combination of Tbs-O-Tf and 2,2′-bipyridyl.

Acetals react with various C-nucleophiles like organocuprates, silyl enol ethers, enamines, and (iso)cyanides via intermediary pyridinium salts.

Initial selective masking of the aldehyde function in ketoaldehydes with PPh3 and TmsOTf permits the selective reduction of the keto function or its alkylation with Grignard reagents followed by deprotection.

A diastereoselective ring contraction of dioxepins (I) in form of a diastereomeric mixture gives cis-tetrahydrofurans (II) with high stereoselectivity.

Tri(o-tolyl)phosphine is identified as a good nucleophile for the formation of intermediate O,P-acetals from O,O-acetals (I) and a good leaving group for the successive nucleophilic substitution.

For preparation of 5-monosubstituted or 5,5-disubstituted 2,4-dienals, 1-(methylthio)-5-(p-tolylsulfonyl)-1,3-pentadiene (4) is revealed to be an important precursor. When 5-(methylthio)-5-(p-tolylsulfonyl)-1,3-pentadiene, that is easily obtainable from (methylthio)methyl p-tolyl sulfone, was treated with silica gel, 1,5-rearrangement of p-tolylsulfonyl group occurred to give 4. The conditions for mono- or dialkylation of 4 followed by hydrolysis leading to the dienals are described.

1-Substituted 1-methylthio-2,4-pentadien-1-yl sulfones ( 4 ) smoothly underwent a 1,5-rearrangement of a sulfonyl group by the action of silica gel. Its application to a new synthesis of conjugated dienones is also described.

The facile deprotection of methylene acetal protection of diols under mild conditions is established. The combination of trimethylsilyl triflate (TMSOTf) and 2,2'-bipyridyl followed by a weakly acidic hydrolysis was effective and the substrates having acid sensitive functional groups can be tolerated under the stated conditions. The selective deprotection between methylene acetal and benzophenone ketal was achieved.

Six new Daphniphyllum alkaloids, calyciphyllines H–M (1–6), were isolated from the leaves and stems of Daphniphyllum calycinum (Daphniphyllaceae). The structures and relative stereochemistry of 1–6 were elucidated on the basis of spectroscopic data, and the absolute stereochemistry of 3 was assigned by PGME method.