Showing papers by "Ernst Schaumann published in 2009"
TL;DR: The use of 3b,c gives a reversal of regioselectivity compared with 3d in the cycloaddition with propriolate 4a (product 9a vs. 2a).
19 citations
TL;DR: The reaction of silyl-substituted carbanions with arene-1,2-dicarboxylates 6, 15 yields indenone derivatives 11, 16 in a domino process involving Silyl C→O migration and elimination.
14 citations
TL;DR: In this paper, it was shown that cyclopropane 4a undergoes ring enlargement to thiochroman 11 and carbene dimer 15, and the suggested singlet character of carbenes 5 was confirmed by DFT calculations (B3LYP/cc-pVTZ).
9 citations
TL;DR: The reaction of a silyl-substituted thioacetal with ortho-difunctionalized benzenes as biselectrophiles allows access to multifunctional cyclooctanols as mentioned in this paper.
4 citations
TL;DR: In this article, a diastereospecific reduction of the corresponding alkynes with DIBAL-H and hydrosilylation with silanes with a potential tosylate or bromide leaving group in the β position is described.
1 citations
15 Sep 2009
TL;DR: In this paper, isocyanate is used to convert oxiranes to 2-oxazolinones, undergoes many cycloadditions; useful for (thio)carbonyl to imine functional group interchange; introduces the Tac protecting group to amino acids.
Abstract: [4083-64-1] C8H7NO3S (MW 197.23)
InChI = 1S/C8H7NO3S/c1-7-2-4-8(5-3-7)13(11,12)9-6-10/h2-5H,1H3
InChIKey = VLJQDHDVZJXNQL-UHFFFAOYSA-N
(converts oxiranes to 2-oxazolinones;2 undergoes many [2 + x] cycloadditions; useful for (thio)carbonyl to imine functional group interchange; introduces the Tac protecting group to amino acids3)
Alternate Name: tosyl isocyanate.
Physical Data: bp 144 °C/10 mmHg; d 1.295 g cm−3.
Solubility: sol chlorinated, aromatic, and ethereal solvents; reacts violently with H2O and basic and protic solvents.
Form Supplied in: colorless liquid; widely available.
Handling, Storage, and Precautions: lachrymator; corrosive; use only in a fume hood. Wear protective gloves and, preferably, a NIOSH-approved respirator. All transfers and reactions should be carried out under anhydrous conditions. Store in a cool dry place, taking care to avoid contamination with protic, basic, or organometallic materials, as these may induce polymerization. See Karol4a and Henderson4b for toxicity data of isocyanates.
TL;DR: The use of 3b,c gives a reversal of regioselectivity compared with 3d in the cycloaddition with propriolate 4a (product 9a vs. 2a) as mentioned in this paper.
Abstract: 1,4-Dihydronaphthalenes 2, 9, and 11 with a spiro-connected 1,3-dithiolane ring as well as tetrahydronaphthalenes 15, 17, and 19 have been obtained from o-quinodimethanes 3 and alkynes 4, naphthoquinones 10, or alkenes 14 and 16. Benzocyclobutenol 6 is not an appropriate quinodimethane precursor as it readily rearranges to phthalaldehyde derivative 7. However, silyl ether 8, silyl ether 13, obtained by the hydrosilylation of cyclobutenol 5, or aluminium alkoxide 3d, generated in situ by DIBAL reduction of 5, are useful sources of the corresponding quinodimethanes. The use of 3b,c gives a reversal of regioselectivity compared with 3d in the cycloaddition with propriolate 4a (product 9a vs. 2a). Naphthoquinone 10 reacts in the cycloaddition with 3b,c through its C2=C3 bond or through a C=O unit to give 11 and 12. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)